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My book says that the batteries we have considered so far (Daniell cells) have a low life span because they reach equilibrium too quickly.
In the next paragraph, it states they are also made by irreversible reactions and we call them "primary batteries."
How can a reaction reach equilibrium without being reversib... |
How can batteries reach equilibrium if the reactions are irreversible? |
Somebody I know insists that the use of a catalyst increases the atom economy. They did chemistry at school and were told that a catalyst increases the atom economy. He pointed me to several past exams where this was written as a valid answer.
However, I am convinced that this is false. After all, atom economy is:
... |
I'm looking for a way to combine two substances in a chemical reaction that uses a lot of energy, therefore absorbing heat, to make a substance cold.
I'm thinking about a two-chamber thermos that in the middle chamber is, for example, juice and in the outside chamber will be placed the other substances. When these s... |
How can I know which way to number the carbon atoms? |
There are three rules to follow for assigning locants (numbers) to a compound like this one.
> 1. Assign locants to generate the longest possible chain of carbon atoms.
Here is an example of mine:
[![enter image description here][1]][1]
I can find chains of eight carbon atoms a few different ways. Two of them... |
I know my teacher told me that
> In adiabatic process there is no exchange for heat between system and surrounding.
Then he came to point. From first law of thermodynamics
$$∆U = q + W \tag{1}$$
Since in adiabatic process there is no heat exchange then,
$$∆U = W \tag{2}$$
And then he said as we know
... |
Adapted from [Chemistry LibreTexts — Strength of Covalent Bonds](https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemistry_-_The_Central_Science_(Brown_et_al.)/08._Basic_Concepts_of_Chemical_Bonding/8.8%3A_Strength_of_Covalent_Bonds), *Table 8.8.1: Average Bond Energies (kJ/mol) for Commonly Encountere... |
Data from [Chemistry LibreTexts — Strength of Covalent Bonds](https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemistry_-_The_Central_Science_(Brown_et_al.)/08._Basic_Concepts_of_Chemical_Bonding/8.8%3A_Strength_of_Covalent_Bonds), *Table 8.8.1: Average Bond Energies (kJ/mol) for Commonly Encountered B... |
May I use water as a condensing medium while distilling out oxalyl chloride?
As Oxalyl chloride reacts with water and the products are HCl, CO and CO2, when there is a leak or breakage of condenser shell/tube separating water and oxalyl chloride, there may be liberation of toxic gases causing the situation more unsa... |
May I use water as a condensing medium while distilling out oxalyl chloride?
As oxalyl chloride reacts with water and the products are $\ce{HCl},$ $\ce{CO}$ and $\ce{CO2},$ when there is a leak or breakage of condenser shell/tube separating water and oxalyl chloride, there may be liberation of toxic gases causing th... |
I got a question in my textbook asking for the mass of Oxygen present in 10.6 grams of Na2CO3. Shouldn't it be the mass of ozone present in 10.6 grams of Na2CO3 ? And if not, then why ? Since O3 is ozone. And what if the question was calculate the mass of ozone present in 10.6 grams of Na2CO3 ? |
What is the mass of ozone present in 10.6 gm of Na2CO3? |
I know my teacher told me that
> In adiabatic process there is no exchange for heat between system and surrounding.
Then he came to point. From first law of thermodynamics
$$∆U = q + W \tag{1}$$
Since in adiabatic process there is no heat exchange then,
$$∆U = W \tag{2}$$
And then he said as we know
... |
The question in the book is about *elemental* composition of the given substance, in terms of mass.
You are given the *empirical* formula, i.e. what could be obtained by elemental analysis, namely what elements composed the substance and in which *relative* ratio. This does not tell you about the spatial arrangement o... |
If we look at the values for the atomic radii (look at the table [here][1]), we can see that they rapidly decrease across the period initially. Looking at the second period,
![enter image description here][2]
The graph is pretty steep early on. But further down the period, as we enter the p-block elements, the g... |
The question in the book is about *elemental* composition of the given substance, in terms of mass.
You are given the *empirical* formula, i.e. what could be obtained by elemental analysis, namely what elements composed the substance and in which *relative* ratio. This does not tell you about the spatial arrangement o... |
In [this question][1], the user asked about curing sodium silicate with calcium chloride. My question is, will the resultant product be insoluble in water? I know calcium silicate is only very slightly soluble, but I'm expecting it's going to be a bit more complicated than that.
[1]: https://chemistry.stackexcha... |
Can sodium silicate be made insoluble? |
In [this answer](https://space.stackexchange.com/a/39247/12102) I've asserted (without a "Chemist's license") that as long as oxygen is above it's critical point in both temperature (154.5 K) and pressure (50.4 bar) it's going to be a supercritical fluid.
[This comment](https://space.stackexchange.com/questions/3923... |
Is oxygen above the critical point always supercritical fluid? Would it still appear to roughly follow the ideal gas law? |
I am currently learning about Alkenes. It is given that cis/trans isomerism is either ambiguous or doesn't even apply in cases where the alkene is trisubstituted or tetrasubstituted. To solve this problem, we make use of the E/Z system of classifying the diastereomers of alkenes. In some cases both the methods of class... |
Why are we still using cis/trans system while the E/Z system is better than it? |
To my understanding beta oxidation is when a fatty acid has its carbons plucked off in groups of 2 (acetyl groups) into acetly-coa which we can dump into the TCA.
At what point would this process stop ? lets say we have a short chain fatty acid like butanoate (4c) would it still transfer an acetyl group leaving an ... |
Other metabolic reactions aside, what causes beta oxidation to stop? |
I got a question in my textbook asking for the mass of oxygen present in 10.6 grams of $\ce{Na2CO3}$. Shouldn't it be the mass of ozone present in 10.6 grams of $\ce{Na2CO3}$? And if not, then why? Since $\ce{O3}$ is ozone. And what if the question was calculate the mass of ozone present in 10.6 grams of $\ce{Na2CO3}$?... |
What is the mass of ozone present in 10.6 g of Na2CO3? |
Suppose an electron in the 2nd shell gets excited and jumps to the 4th shell. Shouldn't the electron then exist in an unstable equilibrium in the 4th shell, than lose energy and drop down to the 2nd shell? What causes it to come out of the equilibrium position and lose energy? The teacher who gave me this problem to th... |
Why does an electron lose energy so that it falls back to a lower energy state than just stay at the higher energy state? |
Vitamin E acetate ((+)-alpha-tocopherol acetate acetate) is sold as [semi-solid/liquid by Sigma][1] and their SDS gives the melting point as 25 °C. On the other hand, internet databases such as [Chemspider show melting points][2] of either -28 °C or 28 °C. Supplements labeled either Vitamin E or Vitamin E oil are packa... |
The order given in my book is
> $$\ce{NH3} > \ce{SbH3} > \ce{AsH3} > \ce{PH3}$$
Phosphorous is more electronegative than arsenic and antimony. Then shouldn't the dipole moment be more in case of $\ce{PH3}?$
And why does the anomaly of $\ce{NH3}$ occur? |
Vitamin E acetate ((+)-alpha-tocopherol acetate) is sold as [semi-solid/liquid by Sigma][1] and their safety data sheet gives the melting point as 25 °C. On the other hand, internet databases such as [Chemspider show melting points][2] of either -28 °C or 28 °C. Supplements labeled either Vitamin E or Vitamin E oil are... |
To add to Alchimista's answer, suppose the question were about a sample containing 1 mole of ozone (and nothing else). You could ask two questions:
1. What is the mass of ozone in the sample?
2. What is the mass of oxygen in the sample?
Because all the oxygen atoms are in the form of ozone, the answer to quest... |
To add to Alchimista's answer, suppose the question were about a sample containing 1 mole of ozone (and nothing else). You could ask two questions:
1. What is the mass of ozone in the sample?
2. What is the mass of oxygen in the sample?
Because all the oxygen atoms are in the form of ozone, the answer to quest... |
What occurs in the following situation: After adding 2 drops of Phenolphthalein Indicator (an indicator that turns bases pink and stays clear for acids,) into a unknown solution, the solution turns pink. However, within a few minutes, the pink slowly fades and the solution becomes colorless. What is the unknown solutio... |
> A $\pu{1.0 L}$ buffer solution of $\mathrm{pH}~4.43$ is made up of $\pu{0.30 M}$ sodium ethanoate and $\pu{0.20 M}$ $\ce{HCl}$ solutions. Calculate the volume of sodium ethanoate and $\pu{0.20 M}$ $\ce{HCl}$ solutions used to prepare this buffer solution.
The answer given for volume of $\ce{HCl}$ is $\pu{750 mL}$ ... |
In sulfur or any atom with an expanded octet on the 3rd row, where does the idea that they have an empty D orbital come from ? |
Sulfur can violate the octet rule because it has an "empty D orbital" is there any other information the periodic table isnt telling us? |
30 ml. Magnesium Hydroxide USP is added to 2 l. carbonated water to make magnesium bicarbonate to be used as a highly bio-absorbable Mg dietary supplement. I'm told the result is 90 mg. elemental Mg per each 4 oz. of this "Magnesium Water."
If one gram of ascorbic acid is added to a small amount of this Mg solution ... |
In [this question][1], the user asked about curing sodium silicate with calcium chloride. My question is, will the resultant product be insoluble in water? I know calcium silicate is only very slightly soluble, but I'm expecting it's going to be a bit more complicated than that.
edit: No, it's not a homework questio... |
I got a question in my textbook asking for the mass of oxygen present in 10.6 grams of $\ce{Na2CO3}$.
Why are they asking about the mass of oxygen? Does this refer to $\ce{O2}$? Shouldn't it be the mass of ozone, $\ce{O3}$, present in 10.6 grams of $\ce{Na2CO3}$, since the formula of sodium carbonate contains three... |
To add to Alchimista's answer, suppose the question were about a sample containing 1 mole of ozone (and nothing else). You could ask two questions:
1. What is the mass of ozone in the sample?
2. What is the mass of oxygen in the sample?
Because all the oxygen atoms are in the form of ozone, the answer to quest... |
It is known that, with regard to the elimination reaction, the Zaitsev product is the thermodynamically more stable product, which is also often the more substituted alkene while the Hofmann product is the thermodynamically less stable product and is usually the less substituted alkene. I have always thought that the s... |
When performing titration between NaOH and H2SO4, both Na2SO4 and NaHSO4 are formed (both are soluble in water), is there any method to obtain crystals of NaHSO4? (Maybe by separating two soluble salts or varying the number of moles of NaOH?) |
It is known that, with regard to the elimination reaction, the Zaitsev product is the thermodynamically more stable product, which is also often the more substituted alkene while the Hofmann product is the thermodynamically less stable product and is usually the less substituted alkene. I have always thought that the s... |
I would like to double check the English grammar of a sentence of an elimination reaction, but I cannot find an answer.
I'd normally say "the elimination of A with X as the leaving group", where A is the initial compound.
So my question is saying "the elimination of X from A", correct? I've never been told not to... |
In [this question][1], the user asked about curing sodium silicate with calcium chloride. My question is, will the resultant product be insoluble in water? I know calcium silicate is only very slightly soluble, but I'm expecting it's going to be a bit more complicated than that.
I'm not a chemist, and wanted to know... |
It is known that, with regard to the elimination reaction, the Zaitsev product is the thermodynamically more stable product, which is also often the more substituted alkene while the Hofmann product is the thermodynamically less stable product and is usually the less substituted alkene. I have always thought that the s... |
I am learning about how to apply group theory analysis of MO diagrams and vibrational in the solid state context (not isolated molecules).
I think the strategy for calculating representations and getting the the orbitals/vibrations with distinct symmetry is quite clear for normal point groups. Essentially you forget... |
How to deal with non-symmorphic space groups for orbital/vibrational analysis? |
This is not the answer OP would expect because I couldn't find metal complexes of type $\ce{[M(H3O)_x]^{y+}}$ (the reason for non-existence(?) is mentioned in the comments) but I did find a complex of an organic compound where hydronium ion act as a ligand i.e a complex of 18-crown-6 and hydronium ion(emphasis mine):
... |
This is not the answer OP would expect because I couldn't find metal complexes of type $\ce{[M(H3O)_x]^{y+}}$ (the reason for non-existence(?) is mentioned in the comments) but I did find a complex of an organic compound where hydronium ion act as a ligand i.e a complex of 18-crown-6 and hydronium ion(emphasis mine):
... |
It seems the [most used way][1] is reaction of sulphuric acid with salts of volatile mineral acids :
$$\ce{H2SO4 + NaCl -> NaHSO4 + HCl ^}$$
Reaction with excess of the acid
$$\ce{H2SO4 + NaOH ->[H2SO4] NaHSO4 +H2O}$$
has several drawbacks:
- It is much more exothermic than the former one
- It releases... |
Sulphur does not expand its octet. That was a hypothesis proposed long ago and vehemently supported by Linus Pauling. While Linus Pauling had a few very great ideas that moved chemistry forward, he also made some major blunders like the octet expansion hypothesis or seven grams of vitamin C a day. Possibly because of P... |
I am conducting a chemistry practical in which I measure the voltage of a Zn-Cu Voltaic cell over time.
Assuming that the surface area of the electrodes are known, concentration of reactants are known, wire resistance is known (Could assume negligible for simplicity).
Is it possible to determine the rate of the re... |
Can the rate of reaction of a Voltaic/Galvanic cell be determined theoretically? |
I have been told that when ∆V=0, work done will be zero (W=0). I know that, in cyclic process ∆V will be zero, since it's a path function and |W| i.e. magnitude of work done will be the area enclosed by the curve. But my doubt is when ∆V=0, shouldn't W also be zero in such processes? |
I am using CO2 for the reduction of pH of NaOH solution (2.5g NaOH + 250ml H2O, with pH 13+).
I am introducing CO2 with different dosages (50cc 100cc, 150cc, 200cc, 250cc, 300cc, 600cc, 900cc, 1200cc 1500cc) using syringe into 35 ml solution of NaOH prepared as mentioned above. The pH first increases and then starts d... |
So, we know that alpha hydroxy ketones give tollens test as the tautomerise into their enol form and the then have an equilibrium between the 2 keto forms.
So going ahead with the same logic. Do alpha hydroxy ketones which can tautomerise to give a methyl ketone group, can they give positive iodoform test? |
Why is my washing powder not to be used for pre-wash? |
There was an [incident in Paris a couple of years ago][1] where a teenage girl during an art lessen got her hands stuck in a bucket with plaster. As the plaster set, the heat from the chemical process caused her fingers to melt (it says in the article that the temperature reached 60° C; I am not sure how this can melt ... |
Can the human body withstand the heat from setting plaster? |
There was an [incident a couple of years ago][1] where a teenage girl during an art lessen got her hands stuck in a bucket with plaster. As the plaster set, the heat from the chemical process caused her fingers to melt (it says in the article that the temperature reached 60° C; I am not sure how this can melt your fing... |
In water, destillation causes fractioning of the O18/O16 oxygen isotopes (https://en.wikipedia.org/wiki/%CE%9418O).
Does something similar happen to the C12/C13 and possibly C14 isotopes in alcohol when it is destilled out of a watery brew? |
Does the destillation of alcohol cause the fractioning of isotopes and C12 enrichement? |
It is commonly known that when zinc metal is placed in a solution of copper (II) sulfate, a displacement reaction occurs, and elemental copper is deposited onto the decomposing zinc metal. A practical demonstration of this shows the zinc turning black from the deposited copper.
My question is, why is the deposited c... |
Why does the displacement reaction of zinc in copper (II) sulfate solution result in dark metallic copper? |
On Wikipedia, it says ammonia has a pKa of 32.5, at -33 deg. C. Why does it say that? All typos? Anything above 12 is a very strong base, correct? And both bases and acids are slightly stronger at higher temperatures not lower, correct? |
Why does ammonia have a pKa of 32.5? At -33 degrees Celsius |
I was in the chemistry lab earlier this week. We were doing a qualitative experiment (no concentration given for any solution).
I added an unknown solution that contains Ba2+, Ca2+, and Mg2+ with (NH4)2SO4, I got barium precipitate and added (NH4)2C2O4 and another precipitate appeared. I was told the second precipit... |
I was in the chemistry lab earlier this week. We were doing a qualitative experiment (no concentration given for any solution).
I added an unknown solution that contains $\ce{Ba^2+},$ $\ce{Ca^2+},$ and $\ce{Mg^2+}$ with $\ce{(NH4)2SO4},$ I got barium precipitate and added $\ce{(NH4)2C2O4}$ and another precipitate ap... |
According to [Wikipedia](https://en.wikipedia.org/wiki/Ammonia), ammonia has a $\mathrm{p}K_\mathrm{a}$ of $32.5$ at $\pu{-33 °C}.$ Why does it say that? Is it a typo? Isn't anything above $12$ is a very strong base? And both bases and acids are slightly stronger at higher temperatures, not lower, correct? |
Why does ammonia have a pKa of 32.5 at −33 °C? |
It is commonly known that when zinc metal is placed in a solution of copper(II) sulfate, a displacement reaction occurs, and elemental copper is deposited onto the decomposing zinc metal. A practical demonstration of this shows the zinc turning black from the deposited copper.
My question is, why is the deposited co... |
Why does the displacement reaction of zinc in copper(II) sulfate solution result in dark metallic copper? |
In water, distillation causes fractioning of the $\ce{^{18}O}/\ce{^{16}O}$ oxygen isotopes ([Wikipedia](https://en.wikipedia.org/wiki/Δ18O)).
Does something similar happen to the $\ce{^{13}C}/\ce{^{12}C}$ and possibly $\ce{^{14}C}$ isotopes in alcohol when it is distilled out of a watery brew? |
Does the distillation of alcohol cause the fractioning of isotopes and carbon-12 enrichment? |
"A gets eliminated" or "the elimination of A" is just plain wrong, typical sloppy lab slang by many (nonnative?) speakers. Very common, but still terrible.
As you say, the small molecule **X** gets eliminated **from** substrate **A**. Chemical English is still just English, and thats the correct way to put the case... |
There was an [incident a couple of years ago][1] where a teenage girl during an art lessen got her hands stuck in a bucket with plaster. As the plaster set, the heat from the chemical process caused her fingers to melt (it says in the article that the temperature reached 60 °C; I am not sure how this can melt your fing... |
There are 12 tetrahedral voids and 6 octahedral voids in hcp unit cell but I can't find any image that can show all tetrahedral voids and all octahedral voids in hcp unit cell (the common picture in Google shows 2 octahedral voids and 3 tetrahedral voids). Could someone help me to draw or find visualization image of al... |
**Assume an ideal gas**
I think we have to assume an ideal gas, otherwise it is not clear how to get the final temperature of the gas. In the OP's comments, the final temperature is determined as 600 K.
**The difference between change in energy and change in enthalpy**
Enthalpy is defined as:
$$H = U + PV$$... |
Since battery scientists got Nobel this week, this question is worth pondering. It is not a trivial question. However consider this question:
A car battery has 12 V, whereas 9 V cells are also common. If we connect two 1.5 V cells and one 9 V cell on series, one can generate 1.5+1.5+9 =12 V, yet this arrangement can... |
Can atomicity be infinity? |
Would you be able to help me understand how to compare and contrast a 2p6 orbital to a 4s1 using quantum numbers to help? |
I would like to double check the English grammar of a sentence of an elimination reaction, but I cannot find an answer.
I'd normally say "the elimination of A with X as the leaving group", where A is the initial compound.
So my question is saying "the elimination of X from A", correct? I've never been told not to... |
I am planning to make **chromic acid**, however I the information for keeping chromic acid are conflicting. Can it be stored in a glass bottle even though it's used as a glass etchant? Also I saw some information that it's dangerous to keep it in plastic containers. What's the common practice? |
Appropriate container for storing/keeping chromic acid? |
Is it really possible for a liquid to stay afloat a gas? |
"A gets eliminated" or "the elimination of A" is just plain wrong, typical sloppy lab slang by many (too often native?) speakers. Very common, but still terrible.
As you say, the small molecule **X** gets eliminated **from** substrate **A**. Chemical English is still just English, and thats the correct way to put t... |
Is it really possible for a liquid to stay afloat a gas (vapor)? |
How would you find the pH of an acid dissolved in water? Would you need to take the fact that the pH of water is already 7 into account and go on from there?
Say, for example, that you add 0.0500 mL of 0.00100 M HCl into 50 L of pure water, what will be the pH of the new solution?
I made the mistake of just fin... |
But if the volume was infinite for gases not enclosed in a container, then how would the ideal gas law even function?
Thanks to anyone who can point out the piece of this puzzle I am not considering! |
If gases assume the volume of the container that they are in, then wouldn't a gas that isn't enclosed in a container have an infinite volume? |
I give you a case. Suppose you opened an airtight jar containing H2 gas. Suppose by some mysterious power, you are able to observe the molecules of the gas. What do you think you'll see on opening the jar?
Obviously you'll see the molecules dissipating in space(the correct word would be diffusing). Initially they supp... |
We are looking at doing planet changing work, and removing CO2 from the atmosphere. The issue is storing the CO2. Please let us know the best ways to compress millions of tons of CO2, as we have limited storage space. For example, how much could we compress a ton of CO2 gas? What size container would a ton of CO2 fit i... |
Best ways to compress and store tons of CO2? |
Is it necessary to add prefixes of halogens (more than 1) to the iupac name alphabetically? |
$2\mathrm{p}^6$, $4\mathrm{p}^1$ are not orbitals.
It is a partial description of an atom electron configuration, saying there are 6 electrons in 3 orbitals $2\mathrm{p}$, respectively 1 electron in the orbital $4\mathrm{s}$.
$2$ in $2\mathrm{p}$ means the (main, energy ) quantum number $n=2$.
$p$ in $2\mathrm{p}$ m... |
$2\mathrm{p}^6$, $4\mathrm{p}^1$ are not orbitals.
It is a partial description of an atom electron configuration, saying there are 6 electrons in 3 orbitals $2\mathrm{p}$, respectively 1 electron in the orbital $4\mathrm{s}$.
$2$ in $2\mathrm{p}$ means the (main, energy ) quantum number $n=2$.
$p$ in $2\mathrm{p}$ m... |
$2\mathrm{p}^6$, $4\mathrm{p}^1$ are not orbitals.
It is a partial description of an atom electron configuration, saying there are 6 electrons in 3 orbitals $2\mathrm{p}$, respectively 1 electron in the orbital $4\mathrm{s}$.
$2$ in $2\mathrm{p}$ means the (main, energy ) quantum number $n=2$.
$p$ in $2\mathrm{p}$ m... |
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