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periodic table | Table for magnetic moments for all elements in periodic table? | https://chemistry.stackexchange.com/questions/112948/table-for-magnetic-moments-for-all-elements-in-periodic-table | <p>I'm trying to look for a table for magnetic moments for all elements of the periodic table for my research project in computational chemistry, can anyone direct me to a suitable one?</p>
| <p>Unpaired electrons will give rise to a magnetic moment equal to the 'spin only' value <span class="math-container">$\mu_s=g\sqrt{S(S+1)}$</span> in units of Bohr Magnetons, <span class="math-container">$e\hbar/2m_e$</span>, for example H atoms with <span class="math-container">$S=1/2$</span>. <span class="math-cont... | 62 |
periodic table | Specific heat capacity and the periodic table | https://chemistry.stackexchange.com/questions/1258/specific-heat-capacity-and-the-periodic-table | <p>Can someone explain me how can I use the periodic table in order to find the specific heat capacities of some elements? (for example, of Aluminium )</p>
<p>The question I have encountered is as follows:</p>
<blockquote>
<p>Given the specific heat capacities of the following liquids, use the periodic table in order t... | <p>Either you have a periodic table that features the specific heat capacity of elements in their standard state at STP (standard temperature and pressure), in which case you merely have to look it up, or you don't, and there's nothing you can do.</p>
<p>Specific heat capacity of materials, even elemental solids, are ... | 63 |
periodic table | Where hydrogen belongs in the Periodic Table | https://chemistry.stackexchange.com/questions/4164/where-hydrogen-belongs-in-the-periodic-table | <p>Why do some people say that hydrogen should be above lithium in the periodic table and others argue it should be above fluorine?</p>
| <p>This comes down to the fact that hydrogen has a $1s$ valence shell, capable of holding only two electrons.</p>
<p>In some sense, hydrogen is like the halogens, in that it can achieve the electronic configuration of a noble gas (namely, helium, which has a full $1s$ level) by gaining an electron. This reduction yiel... | 64 |
periodic table | Periodic table groups - which grouping is "right"? | https://chemistry.stackexchange.com/questions/33453/periodic-table-groups-which-grouping-is-right | <p>In searching online, I've noticed there are a lot of different ways to group the elements of the periodic table.</p>
<p>Take mercury in the two tables linked below, for example:</p>
<ul>
<li><a href="http://i.telegraph.co.uk/multimedia/archive/02101/periodic_2101916b.jpg" rel="nofollow">http://i.telegraph.co.uk/mu... | <p>There is no "most right classification scheme" for the elements of the periodic table, worth memorizing above all others. This is because there is no single, 'universal' set of criteria that effectively, unarguably, and neatly divides the entire periodic table into groups. Depending on the properties of interest, d... | 65 |
periodic table | What do you chemists need from a periodic table? | https://chemistry.stackexchange.com/questions/85676/what-do-you-chemists-need-from-a-periodic-table | <p>I am developing a website and later on an app with the periodic table. The reason I started was that I thought almost all the other periodic tables was awfully ugly.
I do not only want to make it a well-looking periodic table, but I want to make it easy and smart to use combined with the design. </p>
<p><strong>My... | 66 | |
periodic table | Should one pronounce “periodic” the same in “periodic acid” and “periodic table”? | https://chemistry.stackexchange.com/questions/306/should-one-pronounce-periodic-the-same-in-periodic-acid-and-periodic-table | <p>In “periodic table”, the adjective is related to the noun <em>period</em>, and <a href="http://www.etymonline.com/index.php?term=periodic&allowed_in_frame=0" rel="noreferrer">comes from</a> Ancient Greek <em>περίοδος</em> through French <em>périodique</em>. In “periodic acid”, it is formed from the prefix <em>pe... | <p>I am an Australian English speaker and yes, this distinction is made in practice.</p>
<p>Possibly the only reasonable opportunity to use the <code>pɪə</code> pronunciation in the name of a compound is in the case of the entertaining molecule <em>periodane</em>, which is actually named after the periodic table. This... | 67 |
periodic table | What is a "period" of the periodic table? | https://chemistry.stackexchange.com/questions/4529/what-is-a-period-of-the-periodic-table | <p>I'm familiar with the periodic table / periodic system, but I wonder why it's called "periodic" since there seems not much periodic about (there seems to be little or no predictability of which elements are stable) and from physics I know Z-value of elements and that is not periodic either. So what is a "period" in ... | <p>I agree that the "periods" in the periodic table are not mathematically regular. The simplest definition is that a <em>period</em> begins when a new <em>s</em>-subshell starts to fill. Recall that in the <em>s, p, d, f</em> subshells there are 2, 8, 10, and 14 electrons, respectively, so the periods have to get bi... | 68 |
periodic table | Does organic chemistry somehow defy the periodic table? | https://chemistry.stackexchange.com/questions/61680/does-organic-chemistry-somehow-defy-the-periodic-table | <p>My physics lecturer was introducing the idea of what a Theory of Everything was, and said something like this:</p>
<blockquote>
<p>Other sciences have their own theories of everything too, fundamental axioms from which everything else can be derived from. In mathematics, we have ZFC, and well, the entire framewor... | <p>While all chemistry is unified because all chemical compounds are made from things in the periodic table, that isn't like mathematics and much of physics. In these sciences many important complexities are derivable from a simple set of axioms.</p>
<p>Some chemistry is simple to derive or deduce from the periodic ta... | 69 |
periodic table | Confusion with the Periodic Table | https://chemistry.stackexchange.com/questions/34549/confusion-with-the-periodic-table | <p>The periodic table has 7 periods and they have 2,8,8,18,18... elements respectively from 1 to 7. But from what I understand, the periods each state the number of electron shells that the elements in that period has. So if that is the case, shouldn't period 3 have more elements, since it can hold up to 18 electrons, ... | <blockquote>
<p>So if that is the case, shouldn't period 3 have more elements, since
it can hold up to 18 electrons, and therefore it can have up to 18
more protons from the largest atomic number element in period 2?</p>
</blockquote>
<p>Indeed, elements of the same period have the same number of electron shells... | 70 |
periodic table | Pair of analogous periods on the periodic table | https://chemistry.stackexchange.com/questions/7022/pair-of-analogous-periods-on-the-periodic-table | <p>On the periodic table, period 2 and 3, 4 and 5, 6 and 7 and so on have similar blocks, identical length and groups. What are such pairs of analogous periods called?</p>
| <p>In a bit of a web search, there does not seem to be any particular names for families of periods in the Periodic Table. However, according to <a href="http://www.webelements.com/nexus/chemistry_page/periods-periodic-table" rel="nofollow noreferrer">WebElements</a>, </p>
<blockquote>
<p>The f-block elements are a... | 71 |
periodic table | My question is regarding Periodic Table, Why there are three columns for 8B group in old version of the periodic table? | https://chemistry.stackexchange.com/questions/152244/my-question-is-regarding-periodic-table-why-there-are-three-columns-for-8b-grou | <p>Why there are three separate columns for 8B group in old version of the periodic table?</p>
| 72 | |
periodic table | What is the most rare element in periodic table | https://chemistry.stackexchange.com/questions/7462/what-is-the-most-rare-element-in-periodic-table | <p>What is the most rare element in periodic table? I have a lot of confusion about this.</p>
| <p>Well, the first question to answer would be: where? The rarest element in the universe? the sun? in meteorites? on earth? in the ocean? in humans? We can tap in to the curated datasets provided by Mathematica to get the answer:</p>
<p><img src="https://i.sstatic.net/2wSWX.png" alt="Mathematica graphics" /></p>
<p>... | 73 |
periodic table | Confusion regarding trends in modern periodic table | https://chemistry.stackexchange.com/questions/163493/confusion-regarding-trends-in-modern-periodic-table | <p>We know that atomic radius decreases along a period and increases along a group. (Same goes for metallic character)</p>
<p>But if we take 2 elements A & B(A is at somewhere in the top and left in periodic table and B is somewhere is below and right of B) then which among A and B will have greater atomic radius a... | <p>If the period effect for B overrules the group effect, B will have the greater atomic radius than A.</p>
<p>If the group effect for B overrules the period effect, B will have the smaller atomic radius than A.</p>
<p>The same for the element metallic character.</p>
<p>For the p elements, you can see the metalicity bo... | 74 |
periodic table | Electronic configuration and the periodic table | https://chemistry.stackexchange.com/questions/57572/electronic-configuration-and-the-periodic-table | <p>I came across the following question:</p>
<blockquote>
<p>If each orbital can hold a max. of 3 e– what is the number of elements in the 4th period of the periodic table? </p>
</blockquote>
<p>I was unable to even start the thought process of answering the question because I'm rather horrible at discerning the p... | <p>In the 4th period of the periodic table there is 1 s orbital, 3 p orbitals, and 5 d orbitals. That's a total of 9 orbitals. $9 \times 3=27$</p>
<p>That's 27 elements.</p>
| 75 |
periodic table | The "nose" of the periodic table | https://chemistry.stackexchange.com/questions/123729/the-nose-of-the-periodic-table | <p>My teacher said that on the periodic table there is a "nose" formed by Al, Zn, Ag, and Cd. She said that they are all fixed charged (+3, +2, +1, and +2 respectively), and said that if I write them in ionic equations, I just say Silver Nitrate instead of Silver (I) Nitrate. She also said to put all Al as +3 charge in... | <p>All of these elements can form compounds in other oxidation states. Aluminium forms some compounds in the +1 state (e.g. see the section in <a href="https://en.wikipedia.org/wiki/Aluminium_iodide" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Aluminium_iodide</a>), as does Zinc (see the section in <a href=... | 76 |
periodic table | Chemical Formulae and the Periodic Table of Elements | https://chemistry.stackexchange.com/questions/112352/chemical-formulae-and-the-periodic-table-of-elements | <p>Reading about heavy water, I have found that the chemical formula for it can be written 2H<sub>2</sub>O or D<sub>2</sub>O.</p>
<blockquote>
<p>Deuterium is an isotope of hydrogen that is found in large quantities in water, more than one atom per ten thousand hydrogen atoms has a deuterium nucleus. The isotope is ... | <p>According to this entry in the IUPAC Gold book</p>
<p><a href="https://goldbook.iupac.org/html/D/D01648.html" rel="noreferrer">https://goldbook.iupac.org/html/D/D01648.html</a></p>
<p>the symbol for Deuterium is H together with the isotopes notation. </p>
<p>However deuterium and tritium are routinely indicated b... | 77 |
periodic table | According to what criteria was the periodic table of elements ordered? | https://chemistry.stackexchange.com/questions/15926/according-to-what-criteria-was-the-periodic-table-of-elements-ordered | <p>I was wondering why the elements in the periodic table were disposed the way they are. I understand, of course, that they are put in increasing atomic number fashion, but I'd like to know more about the topic. Could you link some reference that examine in detail the structure of the periodic table?</p>
| <p>I do not address the question of history, of Mendeleyev's investigations, that is answered in <a href="https://chemistry.stackexchange.com/questions/15883/how-was-mendeleev-able-to-develop-his-table">How was Mendeleev able to develop his table?</a></p>
<p>Modern understanding of basic principles follows. Let us hav... | 78 |
periodic table | Which is the most reactive element in the periodic table? | https://chemistry.stackexchange.com/questions/53831/which-is-the-most-reactive-element-in-the-periodic-table | <p>Which is the most reactive element in the periodic table? Is it francium, caesium, lithium or fluorine?</p>
| <p>Fluorine is the most reactive non radioactive element on periodic table.</p>
<p>It exists in gaseous form at room temperature and even reacts with glass. So it is almost impossible to store it in pure form.and caesium is the most reactive metal</p>
| 79 |
periodic table | What trends exist in the Periodic Table? | https://chemistry.stackexchange.com/questions/2843/what-trends-exist-in-the-periodic-table | <p>I wish to know the trends in the periodic table and why that trend exists, for the following parameters:</p>
<ol>
<li>Atomic size</li>
<li>Ionization energy</li>
<li>Metallic character</li>
<li>Positive ion size</li>
<li>Negative ion size</li>
<li>Electronegativity</li>
</ol>
<hr>
<p>My progress (if my reasoning ... | <p><ol>
<li>You are correct on atomic size being due to number of electrons
and their <em>shells</em> and the reason why atomic size decreases from
left to right is due to the number of the protons being greater
on the right than on the left of the periodic table with same number of shells due to shell theory. <a href=... | 80 |
periodic table | Diagonal relationships in the Periodic Table | https://chemistry.stackexchange.com/questions/32591/diagonal-relationships-in-the-periodic-table | <p>I have often wondered about diagonal relationships between elements on the periodic table, and the most often cited explanations revolve around charge-density considerations.</p>
<p>But other than that, what other factors could possibly contribute to this phenomenon?</p>
<p><strong>EDIT:</strong> What I mean by "d... | <p>What I remember from studying C-P 'diagonal relationships' (for multiple bonds e.g. carbene vs phosphinidene, alkyne vs phosphaalkyne) is that similar electronegativity also played a role, also by affecting the valence orbitals.</p>
<p>However, perhaps it is better viewed from a different vantage point:
the main gr... | 81 |
periodic table | What is the position of hydrogen in the periodic table? | https://chemistry.stackexchange.com/questions/55464/what-is-the-position-of-hydrogen-in-the-periodic-table | <p>Hydrogen is not in the first group as it was before and it is now placed above the periodic table? So why is it still categorized as a metal in some books?</p>
| <p>There is a lot that could be said about this question, but a simple explanation goes like this:</p>
<ul>
<li><p>Some periodic tables categorize hydrogen as a metal (or at least an alkali metal) because it has one electron in its outermost orbital - just like Lithium, Sodium, Potassium, etc., which are obviously met... | 82 |
periodic table | Periodic Table Group 3 Period 6, 7 | https://chemistry.stackexchange.com/questions/185425/periodic-table-group-3-period-6-7 | <p>I am studying Periodic Table and have doubts in the group 3 (III-B) periods 6 and 7.</p>
<ol>
<li>If f-block is not a part of d-block, then why so they place inner transition metals in the boxes of group 3 periods 6, 7?</li>
<li>Since they place so, why are sometimes La and Ac placed while sometimes Lu and Lr are pl... | <p>I can at least answer your first question, 1). The periodic table developed by Mendeleev is an incredibly useful tool for predicting the physical and chemical properties of elements, but you must understand that it has limitations. I linked the wikipedia page on the history of the periodic table. The page under &quo... | 83 |
periodic table | What is the true depiction of the periodic table? | https://chemistry.stackexchange.com/questions/99223/what-is-the-true-depiction-of-the-periodic-table | <p>Normally with the periodic table the lanthanide series is separated out because it's long and would make the table wide. I looked for an expanded version and found this:</p>
<p><a href="https://i.sstatic.net/VH9ax.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/VH9ax.png" alt="enter image description... | <p>La and Ac have <span class="math-container">$d^1$</span> electrons in their valence shells, rather than <span class="math-container">$f^1$</span> electrons.</p>
<p>The long table you found looks like that for a several reasons.</p>
<p>The trends going down Sc-Y-La are like those seen in groups 1 and 2. The trend g... | 84 |
periodic table | What are the alternatives to the Periodic Table of the Elements? | https://chemistry.stackexchange.com/questions/901/what-are-the-alternatives-to-the-periodic-table-of-the-elements | <p>What are the different diagrams/tables used to organize the elements other than the Periodic Table? What are the advantages/disadvantages of each?</p>
| <p>One periodic table that apparently physicists find useful is ADOMAH periodic table, for its usefulness is finding electron configuration of a particular element. More information at this <a href="http://www.perfectperiodictable.com/userguide" rel="nofollow noreferrer">guide</a>. A disadvantage to this table, along w... | 85 |
periodic table | "Middle row anomaly" of the periodic table | https://chemistry.stackexchange.com/questions/31113/middle-row-anomaly-of-the-periodic-table | <p>I was studying about the periodic table recently, and was reading a topic associated with oxides of halogens, and came across the following line</p>
<blockquote>
<p>The bromine oxides, $\ce{Br2O}$, $\ce{BrO2}$, $\ce{BrO3}$ are the least stable halogen oxides (<strong>Middle row anomaly</strong>) and exist only at... | <p>This is due to the transition metal contraction. </p>
<p>Bromine has the electron configuration $\ce{[Ar] 4s^{2} 3d^{10} 4p^{5}}. $The 3d orbital has no radial nodes and is therefore quite contracted (close to the nucleus), so there is relatively little repulsion between the 3d electrons and the 4p electrons. This ... | 86 |
periodic table | Reading number of outer shell electrons and other properties from periodic table? | https://chemistry.stackexchange.com/questions/31615/reading-number-of-outer-shell-electrons-and-other-properties-from-periodic-table | <p>How can one read from the periodic table the number of outer shell electrons that an atom has, to predict how these atoms will make bonds with other atoms? For example to see that hydrogen ($\ce{H}$) has 1 electron free, while carbon ($\ce{C}$) has 4 and oxygen ($\ce{O}$) has 2? This allows us to infer that carbon c... | <p>Start with a periodic table that shows the electron configurations. You might try the <a href="http://www.ptable.com/" rel="nofollow">Dynamic Periodic Table</a>; as you mouse over an element, its electron configuration is presented. </p>
<p>Then go to <a href="http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml... | 87 |
periodic table | is there any evidence that there are ~75 extra elements on the periodic table? | https://chemistry.stackexchange.com/questions/89409/is-there-any-evidence-that-there-are-75-extra-elements-on-the-periodic-table | <p>there are 118 currently existing elements on the periodic table, and recently I've found like 77 elements that quote on quote "may exist" on our periodic table. Is this true?</p>
| 88 | |
periodic table | Molecular structure of all periodic table element molecules exceptional cases etc | https://chemistry.stackexchange.com/questions/22228/molecular-structure-of-all-periodic-table-element-molecules-exceptional-cases-et | <p>I am searching about some basics in chemistry. I was looking for the molecular structure of all periodic table element molecules.
eg: Hydrogen molecule: as <span class="math-container">$\ce{H2}$</span>; structure:<img src="https://i.sstatic.net/lwUhA.jpg" alt="enter image description here" /></p>
<p>I was able to fi... | <p><img src="https://i.sstatic.net/4R93I.jpg" alt="" /></p>
<p><img src="https://i.sstatic.net/tA50z.png" alt="" /></p>
<p>The noble gases (group <span class="math-container">$18$</span>) are rather inert, so their molecule is just a single atom.</p>
<p>The following elements <strong>usually</strong> consist of molecul... | 89 |
periodic table | Is iron the most stable element in the periodic table? | https://chemistry.stackexchange.com/questions/40407/is-iron-the-most-stable-element-in-the-periodic-table | <p>According to the binding energy per nucleon vs mass number graph, it is observed that iron-56 has the maximum value of binding energy per nucleon ($\pu{8.75 MeV}$). It means that iron-56 is the most efficiently bound nucleus meaning that it has the least average mass per nucleon. This is the approximate basic reaso... | <p>Yes, $^{56}\ce{Fe}$ has the most stable nucleus, and $\ce{He}$ is the most chemically inert element. These are different and unrelated qualities, pretty much like physical fitness and intelligence in a man. As for structural stability, there is no such thing in chemistry (there is one in architecture and another in ... | 90 |
periodic table | Diagonal line going through groups IIIA-VIA on the periodic table | https://chemistry.stackexchange.com/questions/6116/diagonal-line-going-through-groups-iiia-via-on-the-periodic-table | <p>Why is there a diagonal line cutting through some of the nonmetals and metalloids on the periodic table in groups IIIA, IVA, VA, VIA, and VIIA?</p>
<p><img src="https://i.sstatic.net/3zpgH.jpg" alt="Periodic table of elements"></p>
<p>Is there any historical background about it?</p>
| <p><strong>The red line is the <a href="http://en.wikipedia.org/wiki/Dividing_line_between_metals_and_nonmetals" rel="noreferrer">dividing line between metals and non-metals</a></strong>. It is rather arbitrary; as Mendeleev himself wrote: <em>“It is...impossible to draw a strict line of demarcation between metals and ... | 91 |
periodic table | A full verion of the periodic table (For computer game) | https://chemistry.stackexchange.com/questions/7189/a-full-verion-of-the-periodic-table-for-computer-game | <p>I am looking for a full set of data on every element on the periodic table. (and if possible those only speculated about)</p>
<p>When I say full I mean everything. Electron configurations, Valence electrons, melting point, Atomic mass, Isotopes and what they decay into and all the rest.</p>
<p>Is there such a data... | <p>You can find all these information on <a href="http://www.wolframalpha.com" rel="nofollow">Wolfram Alpha</a>. You can use the website directly to obtain these information, and you can call their <a href="http://products.wolframalpha.com/api/" rel="nofollow">API</a> to directly fetch the data online from your own pr... | 92 |
periodic table | Why does hydride acidity increase across period and down group in periodic table? | https://chemistry.stackexchange.com/questions/97667/why-does-hydride-acidity-increase-across-period-and-down-group-in-periodic-table | <p>Why exactly does hydride acidity increase across period and down group in periodic table? What is the explanation with respect to electrons? I can't figure this out because for 1st period etc H is an anion while for the right and middle of the periodic table H is a cation in compounds formed. I feel confused. Does t... | <p>Yes, but that is somewhat circular reasoning, as electronegativity is largely just putting a numerical value to the trends in properties you are observing. A better answer is to compare the effective nuclear charge holding on to the valence electrons as you go across or down the Table. Going across the table, each... | 93 |
periodic table | On the periodic table: Why are groups of elements organized by 'letter' | https://chemistry.stackexchange.com/questions/78557/on-the-periodic-table-why-are-groups-of-elements-organized-by-letter | <p>Why are the groups of elements on the periodic table organized into areas represented by the letters s,p,d,f,g, and h?
What does this mean?</p>
| <p>The letters are related to the electron orbitals, which were originally observed through spectroscopy. <a href="https://en.wikipedia.org/wiki/Electron_configuration" rel="noreferrer">The lines shown in the spectroscope were named <em>sharp</em>, <em>principal</em>, <em>diffuse</em> and <em>fine</em> (or <em>fundamen... | 94 |
periodic table | Why are there 3 columns in Group VIII of the Periodic Table? | https://chemistry.stackexchange.com/questions/50413/why-are-there-3-columns-in-group-viii-of-the-periodic-table | <p>I'm currently reading in-depth about the layout of the Periodic Table, and I wondered why the table has 3 columns in its Group VIII:</p>
<p><a href="https://i.sstatic.net/ThqdHm.png" rel="noreferrer"><img src="https://i.sstatic.net/ThqdHm.png" alt="enter image description here"></a></p>
<p>As I understand, this is... | <p>In the beginning of the <span class="math-container">$20$</span>th century, the periodic table had <span class="math-container">$8$</span> columns, and not <span class="math-container">$18$</span> as today. Electrons and of course <span class="math-container">$spdf$</span> electrons were unknown. The numerous transi... | 95 |
periodic table | Why lanthanides and actinides are shown separate from standard Periodic Table layout? | https://chemistry.stackexchange.com/questions/10478/why-lanthanides-and-actinides-are-shown-separate-from-standard-periodic-table-la | <p>In the standard Periodic Table layout , all the elements up to 56 are in order i.e are in the same layout table. However, lanthanides and actinides are always shown separately from the layout like in this layout:
<a href="https://i.sstatic.net/C4q1r.png" rel="noreferrer"><img src="https://i.sstatic.net/C4q1r.png" al... | <p>The Periodic Table arranges elements in blocks as each type of orbital fills with electrons - $s,p,d,f,g,h$. Alkali metals and alkaline earths are $s$-block filling (but could be one $s$-block slot). $p$-block six electrons to fill are trelides, tetralides, pnticides, chalcogenides, halides, inert gases (but could... | 96 |
periodic table | Why are metalloids found in a zig-zag line on the periodic table | https://chemistry.stackexchange.com/questions/76568/why-are-metalloids-found-in-a-zig-zag-line-on-the-periodic-table | <p>I am confused about the zig-zag pattern of metalloids in the periodic table. Why are metalloids arranged in a zig-zag line? Can anyone answer my question?</p>
| <p>In addition to Pritt Balagopal's answer, in which he has clarified the trends in metallic character across the Periodic Table, I would also like to explain why the metalloids occur in a zig-zag fashion. </p>
<p>Firstly, I would like to again clarify that it is possibly a coincidence that the metalloids start from b... | 97 |
periodic table | In the periodic table, why doesn't the 2nd row have exactly 2 elements? | https://chemistry.stackexchange.com/questions/44640/in-the-periodic-table-why-doesnt-the-2nd-row-have-exactly-2-elements | <p><a href="https://i.sstatic.net/Kysf7.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Kysf7.jpg" alt="enter image description here"></a></p>
<p>Row 1: 2 elements</p>
<p>Row 2: 8 elements</p>
<p>Row 3: 8 elements</p>
<p>Row 4: 18 elements</p>
<p>Row 5: 18 elements</p>
<p>Row 6: 32 elements</p>
<p... | <p>The pattern is better expressed this way:</p>
<pre><code>Row 1: 2 elements
Row 2: 2+6 elements
Row 3: 2+6 elements
Row 4: 2+6+10 elements
Row 5: 2+6+10 elements
Row 6: 2+6+10+14 elements
Row 7: 2+6+10+14 elements
</code></pre>
<p>The reason comes down to how the electrons fill the available energy levels. The thi... | 98 |
periodic table | Why does period 3 of the periodic table contain 8 elements instead of 18? | https://chemistry.stackexchange.com/questions/119812/why-does-period-3-of-the-periodic-table-contain-8-elements-instead-of-18 | <p>Period 1 of the periodic table contains 2 elements (<span class="math-container">$1s^1$</span> and <span class="math-container">$1s^2$</span>).</p>
<p>Period 2 contains 8 elements (<span class="math-container">$2s^1$</span>, <span class="math-container">$2s^2$</span>, <span class="math-container">$2p^1$</span>, <sp... | <p>You could say that the period number tells you about the largest value of principal quantum number in which a electron is present.</p>
<p>Electrons are filled according to <span class="math-container">$n+l$</span> rule. It states as <span class="math-container">$n+l$</span> increases, the energy of the orbital incr... | 99 |
chemical thermodynamics | Best Guide to Chemical Thermodynamics | https://chemistry.stackexchange.com/questions/34724/best-guide-to-chemical-thermodynamics | <p>I understand thermodynamics in a physicsy way - at the level of Callen's <em>Thermodynamics</em>. However, my chemical thermodynamics is quite rusty: concepts like fugacity and activity coefficients are only vaguely familiar from undergrad courses.</p>
<p>I'm looking for a <em>well written, rigorous and succinct</e... | <p>I would suggest:</p>
<p>1) <a href="http://rads.stackoverflow.com/amzn/click/0071247084" rel="nofollow">Introduction to Chemical Engineering Thermodynamics</a> by Smith, Van Ness, and Abbott;</p>
<p>2) <a href="http://books.unbeatablesale.com/chemical_biochemical_engineering_thermodynamics_by_sandler_stanley_i_115... | 100 |
chemical thermodynamics | Intensive properties clarification - Chemical thermodynamics | https://chemistry.stackexchange.com/questions/39499/intensive-properties-clarification-chemical-thermodynamics | <p>I just started learning chemical thermodynamics and have come upon the definitions for extensive and intensive properties. I had a great deal of confusion over the exact meaning of intensive properties, but I believe I have come to a proper understanding of it after doing some extra reading. I will present my unders... | 101 | |
chemical thermodynamics | What is the relation between chemical thermodynamics and chemical kinetics? | https://chemistry.stackexchange.com/questions/44155/what-is-the-relation-between-chemical-thermodynamics-and-chemical-kinetics | <p>Can one be understood on the basis of the other or are they not interrelated at all?</p>
<p>The first thing my kinetics textbook demonstrated was how thermodynamics ignores time taken for a process whereas kinetics considers the time and rate of the process and hence kinetics is a more effective way to view change.... | <p>No. Both I think are equally theoritical or experimental. You must study both seperately. Thermodynamics doesn't speak about rates. While kinetics doesn't tell you stability.
If a reaction produces more than one product, thermodynamics will tell you which is more stable, while that doesn't necessarily mean it is th... | 102 |
chemical thermodynamics | Entropy and Equilibrium Constant: Chemical Thermodynamics | https://chemistry.stackexchange.com/questions/132737/entropy-and-equilibrium-constant-chemical-thermodynamics | <blockquote>
<p>For a reaction taking place in a container in equilibrium with its surroundings, the effect of temperature on its equilibrium constant <span class="math-container">$K$</span> in terms of change in entropy is described by:</p>
<p>(A) With the increase in temperature, the value of <span class="math-contai... | <p>I agree it's not a duplicate because, while you are asking about the same homework problem discussed in the other question you linked, the issue you are having is different. Hence, because the last answer didn't address your specific confusion, you are asking a different question about that same homework problem.</... | 103 |
chemical thermodynamics | Whats the difference between reversible process in thermodynamics and reversible chemical reactions? | https://chemistry.stackexchange.com/questions/108623/whats-the-difference-between-reversible-process-in-thermodynamics-and-reversible | <p>We know that in thermodynamics, reversible process never occur since entropy should be conserved. However, in chemistry we do have a lot of reversed chemical reactions that forms reactants from products, previously formed by a direct reaction. So, what is the misunderstanding here?</p>
| <p>There is no misunderstanding at all.</p>
<p>The second law of thermodynamics can be roughly expressed as: in a given process the entropy of the universe will always increase (defining universe as system + surroundings). </p>
<p><strong>Reversible processes</strong></p>
<p>For reversible processes the entropy of t... | 104 |
chemical thermodynamics | Thermodynamics behind organic chemical reactions? | https://chemistry.stackexchange.com/questions/115221/thermodynamics-behind-organic-chemical-reactions | <p>I took organic chemistry a few years ago at my university, and although I went through the motions to pass the exams, I didn't understand the thermodynamic reasoning behind <em>why</em> the reactions actually occurred. For instance, I memorized that Claisen Condensation reactions occur between two esters in the pres... | <p>Whether or not the product is "more stable" would really depend on the sense in which you consider its reactivity. The <span class="math-container">$\mathrm{p}K_\mathrm{a}$</span> of a <span class="math-container">$\beta$</span>-keto ester is about 11, so in that sense, it is much more reactive than either of the re... | 105 |
chemical thermodynamics | Thermodynamics of a spontaneous isothermal chemical reaction. | https://chemistry.stackexchange.com/questions/106828/thermodynamics-of-a-spontaneous-isothermal-chemical-reaction | <blockquote>
<p>Which of the following is/are correct for spontaneous isothermal
chemical reaction?</p>
<p>(A) <span class="math-container">$\Delta H = 0$</span>, because <span class="math-container">$\Delta T = 0$</span></p>
<p>(B) <span class="math-container">$\Delta S = 0$</span></p>
<p>(C) <span... | <p>The internal energy and enthalpy of a <strong><em>pure</em></strong> ideal gas depends only on temperature. But, the internal energy and enthalpy of an ideal gas <strong><em>mixture</em></strong> depends both on temperature and on the amount of each chemical species that is present. To be more precise, it is equal... | 106 |
chemical thermodynamics | Thermodynamics of chemical reactions "at constant pressure" | https://chemistry.stackexchange.com/questions/138417/thermodynamics-of-chemical-reactions-at-constant-pressure | <blockquote>
<p>Chemical reactions occur at constant temperature and pressure.</p>
</blockquote>
<p>Consider a gaseous, equilibrium reaction: <span class="math-container">$\ce{2NO2(g) <=> N2O4(g)}$</span>. Most questions/textbooks formulate such questions by stating: <em>The reaction happens at (<span class="math... | <p>You have correctly stated the pressure of the system is <span class="math-container">$$p = \frac {(n_1 + n_2)RT}{V}$$</span></p>
<p>But at the end of your question you incorrectly imply the volume is constant and the pressure changes. That is not true. Constant pressure means the external constant pressure ( like th... | 107 |
chemical thermodynamics | Meaning of 'constant T and p' | https://chemistry.stackexchange.com/questions/141929/meaning-of-constant-t-and-p | <p>In chemical thermodynamics, the condition "constant temperature and pressure" appears almost everywhere. However, I felt a small ambiguity in the phrase so I wanted to clear my doubts. When we say "constant <span class="math-container">$T$</span> and <span class="math-container">$p$</span>" in ch... | <p>As a chemical engineer, my perspective on this differs from those of the other responders. I regard a process occurring at constant temperature <em>and</em> pressure as one in which</p>
<ol>
<li><p>The system is held in contact with a constant temperature over the portion of its interface with the surrounding throu... | 108 |
chemical thermodynamics | On the notion of a component in thermodynamics | https://chemistry.stackexchange.com/questions/38896/on-the-notion-of-a-component-in-thermodynamics | <p>Wikipedia article on a <a href="https://en.wikipedia.org/wiki/Component_(thermodynamics)" rel="nofollow">component (in thermodynamics)</a> first mentions that:</p>
<blockquote>
<p>In thermodynamics, a <strong>component</strong> is a chemically-independent constituent
of a system. The number of components repres... | <p>Well, a reaction comes with an equilibrium constant, i.e., mathematically speaking, some equation on constituents. Now we have N unknowns (constituents) and M equations (constraints and equilibrium constants). Supposedly N>M. This means we can't determine all unknowns. To do so, we must fix N-M free variables. These... | 109 |
chemical thermodynamics | Is it really possible for a liquid to stay afloat a gas (vapor)? | https://chemistry.stackexchange.com/questions/122344/is-it-really-possible-for-a-liquid-to-stay-afloat-a-gas-vapor | <p>I have a book at home called <a href="https://www.wiley.com/en-us/Chemical+Thermodynamics+for+Process+Simulation,+2nd,+Completely+Revised+and+Enlarged+Edition-p-9783527343256" rel="nofollow noreferrer">Chemical Thermodynamics for Process Simulation</a> (I have the first edition) and at the very beginning of chapter ... | <p>Yes! Here's a video of Cody floating NaK (liquid) or ethanol/water (liquid) on compressed xenon (gas):
<a href="https://youtu.be/AsP4yMY-a6U" rel="nofollow noreferrer">https://youtu.be/AsP4yMY-a6U</a></p>
| 110 |
chemical thermodynamics | Kinetics vs Thermodynamics | https://chemistry.stackexchange.com/questions/25077/kinetics-vs-thermodynamics | <p>The way kinetics is taught at the undergraduate level (Arrhenius and collision theory) chemical equilibrium is determined governed immensely by activation energy of the reaction. According to thermodynamics, however equilibrium is a function of free energy change. In a way, thermodynamics and kinetics seem to contra... | <p>A great deal of chemistry is determined by the interaction of kinetics and thermodynamics. The world would be a dull place if we didn't have both.</p>
<p>While thermodynamics determines what directions a reaction can go, the kinetics often determines whether the reaction can happen. Take a simple example: diamond i... | 111 |
chemical thermodynamics | Chemical Thermodynamic Functions | https://chemistry.stackexchange.com/questions/82322/chemical-thermodynamic-functions | <p>I'm a high school student with basic knowledge about chemical thermodynamics. I have three questions regarding the thermodynamic state functions $H, S, G$. I have searched a lot in textbooks but they don't give the complete information as to whether the properties taken are that of the system or surroundings.</p>
<... | <p>The three functions you mentioned are applicable only to thermodynamic equilibrium states of the system, for which the pressures and temperatures of the system and its surroundings match one another to within insignificantly small differences. In the integral to get the entropy change (Q2), the same matching applie... | 112 |
chemical thermodynamics | Why are partial molar Gibbs energy and Gibbs energy per mol equal? | https://chemistry.stackexchange.com/questions/5625/why-are-partial-molar-gibbs-energy-and-gibbs-energy-per-mol-equal | <p>I'm not a chemist, but I need some insight into chemical thermodynamics. </p>
<p>In the book that I'm reading <a href="http://www.amazon.co.uk/Physical-Chemical-Equilibrium-Engineers/dp/0470927100/ref=sr_1_1?ie=UTF8&qid=1374225908&sr=8-1&keywords=physical%20and%20chemical%20equilibrium%20for%20chemical%... | <p>The key is that the Gibbs free energy is an extensive quantity. This means that for a single-component system it can be written as
$$ G\left(T,P,N\right) = N\cdot g\left(T,P\right) $$
where <em>N</em> is the number of particles and <em>g</em> is the Gibbs free energy per particle. In other words, if you double the n... | 113 |
chemical thermodynamics | Chemical equilibrium and Le Chatelier Braun for ammonia production | https://chemistry.stackexchange.com/questions/53324/chemical-equilibrium-and-le-chatelier-braun-for-ammonia-production | <p>In the book of Chemical, biochemical and engineering thermodynamics 4th edition from Stanley I. Sandler (Wiley, 2006), there is a problem about the ammonia producing reaction at page 770.</p>
<p>13.17 The simple statement of the LeChatelier-Braun principle
given in Sec. 13.1 leads one to expect that if
the concentr... | 114 | |
chemical thermodynamics | Is light energy defined as work in thermodynamics? | https://chemistry.stackexchange.com/questions/180479/is-light-energy-defined-as-work-in-thermodynamics | <p>Is Light/Radiant Energy considered Kinetic Energy or Potential Energy?</p>
<p>I have started studying Thermodynamics, and the concept of internal energy was introduced, and defined as the sum of kinetic and potential energies of a system.</p>
<p>Another important definition was that:</p>
<p>ΔU = q + w , where</p>
<p... | <p>Absorbing a photon will increase the potential energy of a molecule, and possibly a little kinetic energy change if rotational and vibrational energy is changed in the process. The translational kinetic energy is not changed immediately after absorption (there if no external force to do this) but can be imparted i... | 115 |
chemical thermodynamics | Relation between First Law of Thermodynamics and Ideal Gas Law | https://chemistry.stackexchange.com/questions/119640/relation-between-first-law-of-thermodynamics-and-ideal-gas-law | <p>Thermodynamics has always been a tough thing for me. There are lots of assumptions in this subject (those assumptions, I know, are necessary, I know the science of thermodynamics is a very practical science).<br>
First Law of Thermodynamics states mathematically:
<span class="math-container">$$\Delta U=Q+W$$</span>
... | <blockquote>
<p>Why thermodynamical equations are just for gases?</p>
</blockquote>
<p>They are not. The equation <span class="math-container">$\Delta U = q + P\Delta V$</span> applies to any phase (gas, liquid, solid...) when <em>only</em> pV work is done. In the particular form of the equation you present, the pr... | 116 |
chemical thermodynamics | Alternate formulation of h(P,T)? | https://chemistry.stackexchange.com/questions/166677/alternate-formulation-of-hp-t | <p>I'm using the following handbook <em>"Engineering and Chemical Thermodynamics 2nd edition"</em> by Koretsky. In the book they have an alternate formulation for <em>h(P,T)</em> though it was never explained how they got it (<a href="https://i.sstatic.net/R3HrJ.jpg" rel="nofollow noreferrer">source</a>, equa... | 117 | |
chemical thermodynamics | Thermodynamics potential and differences between them | https://chemistry.stackexchange.com/questions/175333/thermodynamics-potential-and-differences-between-them | <p>There are 5 most common <a href="https://en.wikipedia.org/wiki/Thermodynamic_potential#:%7E:text=It%20is%20the%20energy%20of,from%20an%20expression%20for%20U." rel="nofollow noreferrer">thermodynamics potential</a> -</p>
<p><a href="https://i.sstatic.net/mfkxV.png" rel="nofollow noreferrer"><img src="https://i.sstat... | <p>Note that the term state function is more common that the thermodynamic potential, while both are correct.</p>
<p>Considering <span class="math-container">$U$</span>, <span class="math-container">$H$</span>, <span class="math-container">$F$</span> and <span class="math-container">$G$</span> as different forms of en... | 118 |
chemical thermodynamics | Meaning of chemical potential in chemical reactions | https://chemistry.stackexchange.com/questions/160446/meaning-of-chemical-potential-in-chemical-reactions | <p>In my thermodynamics course, we introduced the chemical potential as a modification of the first + second law of thermodynamics in the case of a system that can exchange particles with its surroundings (consider only PV work):</p>
<p><span class="math-container">\begin{equation}
dU = TdS - pdV + \sum_{j=1}\mu_j dN_j... | 119 | |
chemical thermodynamics | How to measure chemical potential | https://chemistry.stackexchange.com/questions/75115/how-to-measure-chemical-potential | <p>I wonder if there is a way to measure the chemical potential of a substance in a two-component mixture and also to account for its dependence on the number of moles. Explaining it further, suppose there is a mixture of a light component (like methane, C1) and a heavier one (like C20). Given temperature and pressure,... | 120 | |
chemical thermodynamics | Who is Hræðraford, the "learned clerk" "writing in modern chemical Latin"? | https://chemistry.stackexchange.com/questions/14040/who-is-hr%c3%a6%c3%b0raford-the-learned-clerk-writing-in-modern-chemical-latin | <blockquote>
<p><strong>This question has been re-asked on <a href="https://hsm.stackexchange.com/">History of Science and Mathematics</a>:</strong><br>
<a href="https://hsm.stackexchange.com/q/3581">Who is Hræðraford, the “learned clerk” “writing in modern chemical Latin”?</a></p>
</blockquote>
<hr>
<p>Truesdell... | 121 | |
chemical thermodynamics | does LeChatelier's principle contradict the second law of thermodynamics? | https://chemistry.stackexchange.com/questions/186796/does-lechateliers-principle-contradict-the-second-law-of-thermodynamics | <p>suppose a system in chemical equilibrium like ice melting to form water and said water freezing into ice again. it seems to me that a state in chemical equilibrium would have less entropy that a state that isn't in equilibrium since (at least intuitively), the number of microstates that yield a macrostate that isn't... | <p>We can test you assumption that entropy is not maximised at equilibrium by finding the chance that it will be in a non-equilibrium state. We observe that a gas always fills the volume available to reach its equilibrium state. As a test we can find the chance that a gas would fill just <span class="math-container">$9... | 122 |
chemical thermodynamics | Difference between 'homogeneous mixture of several chemical compounds' & 'non-homogeneous system' | https://chemistry.stackexchange.com/questions/37544/difference-between-homogeneous-mixture-of-several-chemical-compounds-non-ho | <p>I just started reading <em>Thermodynamics</em> by Enrico Fermi; he started defining <em>state of a system</em> for <em>homogeneous mixture of several chemical compounds</em> & then <em>non-homogeneous system</em> as: </p>
<p><img src="https://lh3.googleusercontent.com/-h94NSuXpbfc/VfwufkLkYfI/AAAAAAAAAFE/pn6cJB... | <p>You are right that normally a non-homogeneous system would be one where there is boundary between two internally homogeneous phases (like milk which is basically oil and water mixed at a very fine scale).</p>
<p>But Fermi as also allowing for the possibility that there may be only one phase where the concentration ... | 123 |
chemical thermodynamics | Confusion in calculating $\Delta U$ from a bomb calorimeter | https://chemistry.stackexchange.com/questions/144442/confusion-in-calculating-delta-u-from-a-bomb-calorimeter | <p>In the book, it is mentioned the formula for <span class="math-container">$\Delta U$</span> in a bomb calorimeter without any derivation:</p>
<blockquote>
<p><span class="math-container">$$\Delta U = q_v = \frac{Q\times M\times \Delta T}{m}$$</span>
where
<span class="math-container">$$Q=\textrm{heat capacity of cal... | <p>The formula in the book is correct. They are trying to get the change in internal energy per mole of sample. From the first law, for this constant volume system (no work), <span class="math-container">$$\Delta U_{\textrm{total}}=q=C\Delta T$$</span>where C is the heat capacity of the calorimeter. This equation as... | 124 |
chemical thermodynamics | Reference request: review paper / overview of chemical oscillators | https://chemistry.stackexchange.com/questions/70586/reference-request-review-paper-overview-of-chemical-oscillators | <p>I know about the <a href="https://en.wikipedia.org/wiki/Belousov%E2%80%93Zhabotinsky_reaction" rel="nofollow noreferrer">Belousov-Zhabotinskii reaction</a> as an example of "chemical oscillator", e.g. a reaction that can produce repeating patterns over time as it exhausts its reagents. I also know about the <a href=... | 125 | |
chemical thermodynamics | Which salts precipitate from a potassium/sodium chloride/sulfate solution? | https://chemistry.stackexchange.com/questions/134484/which-salts-precipitate-from-a-potassium-sodium-chloride-sulfate-solution | <p>This is not a homework question. I am not in any course of study. The following question arises from my personal curiosity. If 1 mole of sodium sulfate and 2 moles of potassium chloride are dissolved in water, and the solution is gradually evaporated, which salts precipitate, and in which order?</p>
<p>There are fo... | 126 | |
chemical thermodynamics | Physical significance of chemical potential and fugacity | https://chemistry.stackexchange.com/questions/145224/physical-significance-of-chemical-potential-and-fugacity | <p>I'm studying equilibria and thermodynamics and came across these two terms.</p>
<p>My problem is, unlike other thermodynamic properties that I can understand physically like volume, pressure, enthalpy etc. <em>do these two quantities have physical significance</em> or, is it just that we define fugacity (without any... | <p>The chemical potential is the partial derivative of the Gibbs free energy with respect to the number of moles of the specified species at constant T, P, and numbers of moles of all other species. The equation you wrote is the what this partial derivative reduces to for a species in an ideal gas mixture, where P is ... | 127 |
chemical thermodynamics | What is the difference between standard chemical potential (μ standard) and the "pure" chemical potential (μ*)? | https://chemistry.stackexchange.com/questions/49197/what-is-the-difference-between-standard-chemical-potential-%ce%bc-standard-and-the | <p>I am studying solutions for my thermodynamics course and I am a little confused about the chemical potential of a solute. I found the following from Atkins:</p>
<blockquote>
<p>For a solute $\ce B$,obeying Henry's Law $p_\ce B=K_\ce B\, x_\ce B$, where $x_\ce B$ is the molar fraction</p>
</blockquote>
<p>$$\mu ... | 128 | |
chemical thermodynamics | Will all thermodynamic equations have a linear dependence with moles? | https://chemistry.stackexchange.com/questions/26785/will-all-thermodynamic-equations-have-a-linear-dependence-with-moles | <p>I'm taking chemical thermodynamics this semester, and currently seeing things like the Maxwell's Relations.</p>
<p>My professor never uses explicitly the variable "n" and always works with molar quantities like $\bar{V}$ and stuff like that.</p>
<p>I think this simplifies the algebra a great deal, and can be usefu... | <p>Extensive properties actually have a linear dependence with the common magnitudes used for amount of substance.</p>
<p>Mathematical speaking, you work in some representation in which one magnitude is represented with a function of some variables, and the later represent other physical variables. For example $S(U,V,... | 129 |
chemical thermodynamics | Understanding Chemical Potential (Li-ion) | https://chemistry.stackexchange.com/questions/66863/understanding-chemical-potential-li-ion | <p>Can anyone help me to understand what the "Chemical Potential" is? I can see that in batteries the electrical energy is stored as "chemical potential", according to <a href="http://www.sciencedirect.com/science/article/pii/S1369702115003181" rel="nofollow noreferrer">this</a>:</p>
<blockquote>
<p... | 130 | |
chemical thermodynamics | Integration of chemical potential | https://chemistry.stackexchange.com/questions/136948/integration-of-chemical-potential | <p>I want to ask a question about chemical potential, <span class="math-container">$\mu$</span>.</p>
<p>I dislike the use of integrals to describe quantities in thermodynamics. If we observe the definition of chemical potential for constant pressure:</p>
<p><span class="math-container">$$\mu_i = \left(\frac{\partial G}... | 131 | |
chemical thermodynamics | Where does the thermal energy come from in a chemical change when two substances react with one another? | https://chemistry.stackexchange.com/questions/41664/where-does-the-thermal-energy-come-from-in-a-chemical-change-when-two-substances | <p>We're learning about chemical reactions in class and we recently did an experiment where we combined copper and nitric acid. Both were at relatively room temperature and when they were combined the temperature rose very quickly. Isn't this contradicting the first law of thermodynamics? If the thermal energy is neith... | <p>The energy was in the chemicals, in the form of bonds. Energy is liberated when there is bond formation. As the reaction between $\ce{Cu}$ and $\ce{HNO3}$ is feasible at room temperature so it happened. </p>
<p>And another thing, room temperature is a nice temperature for that reaction because first we need to brea... | 132 |
chemical thermodynamics | Proving a thermodynamic relation between $(\partial H/\partial T)_p$ and $(\partial U/\partial T)_V$ | https://chemistry.stackexchange.com/questions/126955/proving-a-thermodynamic-relation-between-partial-h-partial-t-p-and-part | <p>(This question is taken from Problem 1.1(b) of the book Chemical Thermodynamics: Principles and Applications.)<span class="math-container">$\require{begingroup} \begingroup \newcommand{\pd}[3]{\left(\frac{\partial #1}{\partial #2}\right)_{\!#3}}$</span></p>
<blockquote>
<p>Prove <span class="math-container">$$\pd... | <p><span class="math-container">$\require{begingroup} \begingroup \newcommand{\pd}[3]{\left(\frac{\partial #1}{\partial #2}\right)_{\!#3}}$</span></p>
<p>I would start from</p>
<p><span class="math-container">$$ dH = \pd HTp dT + \pd HpT dp$$</span></p>
<p>This gives rise to </p>
<p><span class="math-container">$$ ... | 133 |
chemical thermodynamics | Fundamental equation of thermodynamics for magnetocaloric materials | https://chemistry.stackexchange.com/questions/33329/fundamental-equation-of-thermodynamics-for-magnetocaloric-materials | <p>The fundamental equation of thermodynamics, as us chemists (and chemical engineers!) are used to seeing it, is </p>
<p>$$ dG = - S~dT + V~dP + \sum_{i}\mu_i~dN_i$$</p>
<p>This gives the Gibbs free energy as a function of temperature, pressure, and composition, <em>assuming there are no other relevant forces other ... | <p>The fundamental equation for paramagnetic system is as follows<br>
$$dU=TdS+BdM+\mu dN$$<br>
Where B is the external magnetic field intensity and M is the magnetic moment (Here I have neglected the P-V work of the system). For your chemically pure and non-reactive system the above equation simplifies to<br>
$$dU=TdS... | 134 |
chemical thermodynamics | What is the true meaning of Gibbs energy and chemical potential? | https://chemistry.stackexchange.com/questions/122162/what-is-the-true-meaning-of-gibbs-energy-and-chemical-potential | <p>After doing some research and reading I found some problems which I will try to state as clearly as possible. </p>
<p>The definition of Gibbs Free Energy says "<em>the greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing ... | <p>Your first question:</p>
<p>Before the second law was understood it used to be thought that the maximum amount of work that could be extracted from a reaction was <span class="math-container">$-\Delta H$</span> but many experiments showed that this was not the case. It is true that, according to the first law, (the... | 135 |
chemical thermodynamics | Why is electrochemical potential defined as sum of electrical potential and apparent electrical potential energy? | https://chemistry.stackexchange.com/questions/174677/why-is-electrochemical-potential-defined-as-sum-of-electrical-potential-and-appa | <p>Engel and Reid's <em>Physical Chemistry</em> [1, p. 308] defines the electrochemical potential in terms of the charge in units of the electron charge <span class="math-container">$(z),$</span> Faraday constant <span class="math-container">$(F),$</span> and electrical potential <span class="math-container">$(\phi)$</... | <p>The chemical potential of a substance <span class="math-container">$i$</span> in a system is generally defined in relation to the Gibbs energy differential:</p>
<p><span class="math-container">$$\mathrm{d}G = \left( \frac{\partial G}{\partial n_i} \right)_{T,p}\mathrm{d}n_i = \mu_i\ \mathrm{d}n_i \tag{1}$$</span></... | 136 |
chemical thermodynamics | How to derive the chemical potential of an ideal solution of a non-volatile solute? | https://chemistry.stackexchange.com/questions/184433/how-to-derive-the-chemical-potential-of-an-ideal-solution-of-a-non-volatile-solu | <p><span class="math-container">$ΔG=-nFe$</span> (<a href="https://chemistry.stackexchange.com/questions/72457/why-delta-g-nfe-and-not-f-integraldne/176835#176835">example</a>) and <span class="math-container">$μ = μ° + RT\ln a$</span> are used very frequently in chemical thermodynamics.</p>
<p>However, if the Gibbs en... | <p>I think I was able to solve the problem myself using the following method:</p>
<p><strong>●The chemical potential of an ideal gas</strong> is:
<span class="math-container">$$\mu=\mu_0+RT\ln\left(\frac{P}{P_0}\right) \tag{0-1}$$</span></p>
<p>Where,</p>
<ul>
<li><span class="math-container">$\mu$</span>: Chemical pot... | 137 |
chemical thermodynamics | Why does the formula for chemical potential change? | https://chemistry.stackexchange.com/questions/188654/why-does-the-formula-for-chemical-potential-change | <p>In thermodynamics, to find the expression for the chemical potential of a pure gas, we can find this expression:</p>
<p><span class="math-container">$$\frac{\mathrm d\mu}{\mathrm dP} = \frac{\mathrm dV}{\mathrm dn} = \frac{RT}{P} \quad \text{(from $\frac{\mathrm dg}{\mathrm dP} = V$)}.$$</span></p>
<p>But why does t... | <p>Gibbs' theorem tells us that the partial molar free energy (chemical potential) of a species in an ideal gas mixture is the same as that of the pure species at the same temperature and at a pressure equal to the partial pressure of the species in the gas mixture. So, <span class="math-container">$$\mu=\mu^0(T)+RT\l... | 138 |
chemical thermodynamics | Can chemical potential be directly measured like this? | https://chemistry.stackexchange.com/questions/167457/can-chemical-potential-be-directly-measured-like-this | <p>I have a system of a pure ideal gas <span class="math-container">$a$</span>, which I call 'the reference', with a known <span class="math-container">$P^{ref}, V^{ref}, T^{ref}$</span> and <span class="math-container">$n^{ref}_a$</span>. I know the chemical potential formula for an ideal gas, so can calculate how it ... | 139 | |
chemical thermodynamics | In which order should I learn Thermodynamic | https://chemistry.stackexchange.com/questions/127738/in-which-order-should-i-learn-thermodynamic | <p>I study physical chemistry on my own and I have to decide in which order I learn the following topics
These are my topics:</p>
<p>Statistical Thermodynamics (especially entropy, partition function, Boltzmann factor..)/
Maxwells Relations/
Thermodynamic Potentials/
Chemical potential/
Colligative properties/
Kinetic... | <p>Take any common PC book, and follow the order given therein.</p>
<p>It usually starts with ideal gas equation, enthalpy, entropy, Gibbs, chemical potential, i.e. plain thermodynamics. (that lecture was called <strong>PC1</strong> at my alma mater)</p>
<p>On top of that, you can add kinetics and statistics (<strong... | 140 |
chemical thermodynamics | Why are equilibrium constants unitless? | https://chemistry.stackexchange.com/questions/1137/why-are-equilibrium-constants-unitless | <p>I haven’t quite reached the point where I can read a full-fledged text on chemical kinetics and thermodynamics yet, so bear with me, please. </p>
<p>I’m wondering why a value like $K_\text{eq} = \frac{[\ce{NO}]^2[\ce{O2}]}{[\ce{NO2}]^2}$ wouldn't have units of M?</p>
| <p>I goofed up the first time I tried to answer this question, erroneously applying dimensional analysis to your equilibrium expression.</p>
<p>It turns out that Silberberg<sup>[1]</sup> gives a good explanation of why $K_\text{eq}$ is dimensionless, which is often glossed over as the terms of the equilibrium expressi... | 141 |
chemical thermodynamics | Do the differential expressions of second law of thermodynamics imply a smooth increase in entropy? | https://chemistry.stackexchange.com/questions/152616/do-the-differential-expressions-of-second-law-of-thermodynamics-imply-a-smooth-i | <p>Another statement of second law of thermodynamics can be formulated in terms of system properties and not properties + surroundings (isolated system). For a closed system at constant temperature and pressure:</p>
<p><span class="math-container">$$dG_{T,p,n_i} \leq 0$$</span></p>
<p><strong>Are <span class="math-cont... | 142 | |
chemical thermodynamics | Entropy Changes in Electrolytic/Galvanic Cell? | https://chemistry.stackexchange.com/questions/151090/entropy-changes-in-electrolytic-galvanic-cell | <p>One of the most fundamental equations in chemical thermodynamics states: <span class="math-container">$$ \Delta_rH_m^⦵ = \Delta_rG_m^⦵ + T\Delta_rS_m^⦵ $$</span>
If we look at this equation in context of net chemical reaction in electrolytic or galvanic cell, it is usually interpreted as follows: Enthalpy of reactio... | <blockquote>
<p>[OP] One of the most fundamental equations in chemical thermodynamics states: <span class="math-container">$$ \Delta_rH_m^⦵ = \Delta_rG_m^⦵ + T\Delta_rS_m^⦵ $$</span></p>
</blockquote>
<p>This is just the definition of the Gibbs energy. By itself, it does not give you any insight into chemical reactions... | 143 |
chemical thermodynamics | Concept of Absolute Thermodynamic Activity | https://chemistry.stackexchange.com/questions/172573/concept-of-absolute-thermodynamic-activity | <p>In the textbook Electrochemical Systems by Newman and Alyea, Chapter 14: The definition of some thermodynamic functions, chemical potential of component (ionic or neutral) is written as a function of absolute activity: <span class="math-container">$$\mu_i=RT\ln \lambda_i \tag{1}$$</span></p>
<p>where <span class="ma... | <p>Using the definition of the absolute activity provided by <a href="https://goldbook.iupac.org/terms/view/A00019" rel="nofollow noreferrer">IUPAC</a></p>
<p><span class="math-container">$\mu_i=RT\ln \lambda_i \tag{1}$</span></p>
<p><span class="math-container">$\mu_i^\circ=RT\ln \lambda_i^\circ \tag{2}$</span></p>
<p... | 144 |
chemical thermodynamics | What prevents everyday objects from reacting? | https://chemistry.stackexchange.com/questions/71387/what-prevents-everyday-objects-from-reacting | <p>This may be a stupid question but I would like to know what prevents chemical reactions from happening among common objects in everyday life? The opposite would be, what requirements must be met for chemical reactions?</p>
<p>For example, as I am typing this what prevents no reaction between my fingers and the keyb... | <p>As I see it, two factors: <em>thermodynamics</em> and <em>kinetics</em>. </p>
<p><strong>Thermodynamics</strong>: Many of the reactions that "don't happen" in everyday life are not favored thermodynamically, we call them <em>non-spontaneous</em>. This means that the products would be higher in energy than the react... | 145 |
chemical thermodynamics | Proving a relation for fugacity of component i in term of independent variables (T,V) | https://chemistry.stackexchange.com/questions/112989/proving-a-relation-for-fugacity-of-component-i-in-term-of-independent-variables | <p>In <em>Molecular Thermodynamics of fluid phase equilibria</em> by Prausnitz et al. [1] the authors recommend to use the following equation which gives the fugacity of component <span class="math-container">$i$</span> in terms of independent variables <span class="math-container">$V$</span> (volume) and <span class="... | <p>I haven't been able to work out all the details of the mathematics yet, but the derivation of this equation must start out from the following equation: </p>
<p><span class="math-container">$$nRT\mathrm{d}\ln{\phi} = (V - V^{ig})\mathrm{d}P,$$</span></p>
<p>where <span class="math-container">$\phi$</span> is the f... | 146 |
chemical thermodynamics | Will addition of inert gas change the vapour pressure of a liquid? | https://chemistry.stackexchange.com/questions/152504/will-addition-of-inert-gas-change-the-vapour-pressure-of-a-liquid | <p>From this question on Physics SE <a href="https://physics.stackexchange.com/questions/7284/">Thermodynamics of evaporation</a>:</p>
<blockquote>
<p>Now imagine the experiment is repeated but instead of vacuum conditions, the water is pressurized with nitrogen at 1 atm. According to the phase diagram of water, liquid... | <p>If the nitrogen is truly inert, its presence will have <em>no <strong>direct</strong> effect on the chemical potential of the water in the gas phase</em>. Essentially, the gaseous water is "unaware" of the nitrogen. Consistent with this, in a mixture of ideal gases, the chemical potential of each gas is ... | 147 |
chemical thermodynamics | How can we justify setting the affinity $\sum_i \mu_i \nu_i$ equal to zero at chemical equilibrium? | https://chemistry.stackexchange.com/questions/14012/how-can-we-justify-setting-the-affinity-sum-i-mu-i-nu-i-equal-to-zero-at-ch | <p>Let $\sum_A \nu_A A \rightarrow \sum_B \nu_B B$ be a general reaction whose progress during time interval $dt$ is measured by $d\zeta$, so the amount of reactants consumed and products generated in mole would be $d N_i=\nu_i d\zeta$, wherein, $\nu_i$ would take negative values for the reactants being consumed.</p>
... | <p>Chemical equilibrium is a stable equilibrium, i.e. the system returns to equilibrium to whatever perturbations. This also leads to the condition of equilibrium, as it should contain this information.</p>
<p><strong>The short answer to your question:</strong></p>
<p>Due to the stability, the system stays/returns t... | 148 |
chemical thermodynamics | How are partial molar Gibbs excess functions correctly defined? | https://chemistry.stackexchange.com/questions/36875/how-are-partial-molar-gibbs-excess-functions-correctly-defined | <p>I <em>think</em> I've found a mistake in my thermodynamics textbook, <em>Chemical Thermodynamics for Process Simulation</em>, but as thermodynamics is hard and I'm a relative novice, I wanted to check here.</p>
<p>The textbook, in talking about partial molar Gibbs excess functions of species in solutions, writes th... | <p>The confusion is perhaps not uncommon. However, whichever book it is has jumped from discussing the free energy of pure materials, and their variation with various things (T, P, V, ...), to discussing mixtures. In this case, all variation of the 'pure' substances is present in the ideal terms - that is because thos... | 149 |
acid base equilibrium | Acid-base equilibrium of NH4CN | https://chemistry.stackexchange.com/questions/14857/acid-base-equilibrium-of-nh4cn | <p>I'm having difficulties understanding this problem.</p>
<p>We have in the problem that $K_\mathrm a$ for $\ce{HCN} = 6.2\cdot10^{-10}$ and $K_\mathrm b$ for $\ce{NH3} = 1.8\cdot10^{-5}$.</p>
<ol>
<li>Write chemical equations to represent the dissociation of $\ce{NH4CN}$ in water, and the acid-base equilibrium equa... | <p>Fun! weak acid versus weak base!</p>
<p>Ammonium cyanide, <span class="math-container">$\ce{NH4CN}$</span>, is a solid where the atoms are grouped into the same ions that are generated in solution: <span class="math-container">$\ce{NH4+}$</span> and <span class="math-container">$\ce{CN-}$</span>. Although it can b... | 150 |
acid base equilibrium | Acid - Base Equilibrium | https://chemistry.stackexchange.com/questions/51834/acid-base-equilibrium | <p>Suppose we had a closed system proceeding according to, </p>
<p>$$\ce A +2\ce B \rightleftharpoons 2 \ce C$$</p>
<p>And that three experiments produced the following concentration data. </p>
<p>Experiment 1:</p>
<p>\begin{array}{|c|c|} \hline
{\rm \small Species} & {\rm \small concentration} \\\hline
\ce A &... | <p>You have an error somewhere in your math.</p>
<p>Assuming you were supposed to interpolate <span class="math-container">$K_C$</span> from both experiment 1 and 2, you would do the following:
Experiment1 yields <span class="math-container">$K_C=3.31$</span>. Experiement two yields <span class="math-container">$K_C=3.... | 151 |
acid base equilibrium | Notation for acid-base reactions of differing strengths - equilibrium? | https://chemistry.stackexchange.com/questions/165665/notation-for-acid-base-reactions-of-differing-strengths-equilibrium | <p>I'm having trouble finding anything meaningful in textbooks or searches. My question is what is the correct notation for writing acid-base reactions when their strengths are varying? I know that theoretically all reactions are reversible but when is it appropriate to use equilibrium arrows for certain acid-base reac... | 152 | |
acid base equilibrium | Equilibrium constant expression for an acid base reaction | https://chemistry.stackexchange.com/questions/150940/equilibrium-constant-expression-for-an-acid-base-reaction | <p>While reading an organic chemistry textbook I saw the following Formula for calculating equilibrium constant of an acid-base reaction</p>
<p>Consider following acid base reaction in which <span class="math-container">$\ce{HA}$</span>(reactant acid) and <span class="math-container">$\ce{HB+}$</span>(product acid) ar... | <p>The issue as I can see it here is a simple misunderstanding that can rectified:</p>
<p><span class="math-container">$K_\mathrm a$</span> is a constant even if <span class="math-container">$\ce{[A]}$</span> is not. (which is how it was defined)</p>
<p>The definition of <span class="math-container">$k_\mathrm a$</span... | 153 |
acid base equilibrium | Calculating equilibrium constant for a general acid base reaction | https://chemistry.stackexchange.com/questions/171444/calculating-equilibrium-constant-for-a-general-acid-base-reaction | <p>I am trying to find the equilibrium value for different acid-base reactions. I have understood that when an acid and base are in an aqueous solution, many different reactions will occur. By combining these reactions, and multiplying their equilibrium constants, we can find the equilibrium value for an acid-base reac... | <p><strong>The rule No 0:</strong> Learn to enumerate chemical reactions. The prerequisite is the knowledge of arithmetic of small natural numbers. Total charges and total atom counts must be equal on both reaction sites. No atom is created nor destroyed during any chemical reaction.</p>
<p><strong>The rule No 1:</stro... | 154 |
acid base equilibrium | Can equilibrium be calculated at any time of an acid base reaction and still be the same? | https://chemistry.stackexchange.com/questions/108602/can-equilibrium-be-calculated-at-any-time-of-an-acid-base-reaction-and-still-be | <p>Should the equilibrium constant <span class="math-container">$K$</span> be calculated at the end of an acid-base titration or can we calculate it in the middle of the titration for example? If so, will the calculated equilibrium constant be equal to the equilibrium constant calculated from the final state of the tit... | <p>Because proton transfers are very fast, the equation <span class="math-container">$K_a=\frac{[\text{conjugate base}][\ce{H+}]}{[\text{acid}]}$</span> will always hold as long as your solution is well mixed. So if you are able to measure those three concentrations, you can determine <span class="math-container">$K_a$... | 155 |
acid base equilibrium | How to justify this contradiction in acid-base equilibrium of methanol and water? | https://chemistry.stackexchange.com/questions/94188/how-to-justify-this-contradiction-in-acid-base-equilibrium-of-methanol-and-water | <p>Let's talk about the following compounds - water and methanol. </p>
<ol>
<li><p>We know that <em>methanol is slightly more acidic than water</em>, because water's ability to donate a proton as an acid is reduced due to extensive hydrogen bonding.
The $\mathrm{p}K_\mathrm{a}$ values are approximately $15.5$ and $15.... | <blockquote>
<ol>
<li><p>We know that methanol is slightly more acidic than water, because water's ability to donate a proton as an acid is reduced due to extensive hydrogen bonding. [...]</p>
</li>
<li><p>[...] It is very clear that methoxide is a stronger base compared to hydroxide, due to the +I (inductive) effect o... | 156 |
acid base equilibrium | Derivation of relation between acid and base equilibrium constants | https://chemistry.stackexchange.com/questions/65255/derivation-of-relation-between-acid-and-base-equilibrium-constants | <p>While deriving the relation between $K_a$ and $K_b$ in ionic equilibrium topic, say I take an example of</p>
<p>$$
\ce{NH4+ + H2O -> NH3 + H3O+} \tag{1}\label{1}
$$</p>
<p>The $K_a$ of this reaction is:</p>
<p>$$
\frac{\ce{[NH3][H3O+]}}{\ce{[NH4+][H2O]}}
$$</p>
<p>Now $\ce{NH3}$ is a conjugate base of $\ce{NH... | <ol>
<li><p>$K_\mathrm{a}$ and $K_\mathrm{b}$ should not have a term for the concentration of water inside.</p></li>
<li><p>When you dissolve $x$ moles of $\ce{NH3}$ in water (doesn't matter how much $x$ is), both relations</p></li>
</ol>
<p>$$K_\mathrm{a} = \frac{[\ce{NH3}][\ce{H3O+}]}{[\ce{NH4+}]} \tag{1}$$</p>
<p>... | 157 |
acid base equilibrium | Why don't buffer solutions return to equilibrium? | https://chemistry.stackexchange.com/questions/101085/why-dont-buffer-solutions-return-to-equilibrium | <p>Suppose I want to make a buffer solution in any of the three ways possible with dihydrogen phosphate as my weak acid. In the first way, a certain ratio of the weak acid and its conjugate base are added at once to form the buffer. Why does this not return to the equilibrium described by its Ka value instead of formin... | <p>Let us consider the standard acetic acid/sodium acetate buffer, with, say, 0.1M of acetic acid and 0.1M of sodium acetate. These are not the equilibrium concentrations of acetic acid and sodium acetate; the buffer solution will equilibrate. In this case, the pKa of acetic acid being less than 7, we know that some ac... | 158 |
acid base equilibrium | Can we estimate acid base reaction equilibrium in non aqueous media? | https://chemistry.stackexchange.com/questions/188241/can-we-estimate-acid-base-reaction-equilibrium-in-non-aqueous-media | <p>My former question <a href="https://chemistry.stackexchange.com/questions/188136/is-deprotonation-limiting-the-product-formation-in-this-thiohydantoin-synthesis">Is deprotonation limiting the product formation in this thiohydantoin synthesis?</a>
made me wonder to what extent the KOH deprotonates the imide (pka 8)? ... | 159 | |
acid base equilibrium | How do you make sense of acid base reactions in organic chemistry? | https://chemistry.stackexchange.com/questions/71300/how-do-you-make-sense-of-acid-base-reactions-in-organic-chemistry | <p>My question is in regards to acid base reaction that take place in larger chemical reaction in orgo. Like, I understand acid base reaction, how to qualitatively check which is stronger acid or base or where equilibrium lies, very well. But i feel that when I am trying to study the mechanism of series of other reacti... | <p>The answer to both questions lies in the fact that a reaction can be directed to a certain extent by controlling the concentration of the reagents. The first reaction is perfectly fine since <strong><em>an alkoxide ion is more basic than a hydroxide ion.</em></strong> As for the second reaction, <strong><em>a carbo... | 160 |
acid base equilibrium | Acid/Base dissociation constants relationship | https://chemistry.stackexchange.com/questions/41696/acid-base-dissociation-constants-relationship | <p>From what I understand, the concentration of hydronium and hydroxide molecules is constant in pure water (and equals $10^{-7}\ \text{M}$, which is measured experimentally). </p>
<p>What I don't understand is why this remains true for an aqueous solution with an acid or base in it. Shouldn't it affect these concentr... | <p>The concentrations do change in the presence of acid or base and are no longer $10^{-7}$M.</p>
<p>Instead, [H3O+][OH-] $= 10^{-14}M^2$</p>
<p>This comes from: </p>
<p>$\ce{2H2O <=> H3O+ + OH-}$</p>
<p>$K = \frac{a(\ce{H3O+})a(\ce{OH-})}{(a(\ce{H2O}))^2}$</p>
<p>Where "a(x)" is activity of species "x". </... | 161 |
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