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[url=https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/Solutions_and_Mixtures/Nonideal_Solutions/Introduction_to_Non-ideal_Solutions#:~:text=A%20non%2Dideal%20solution%20is,between%20molecules%... |
When is the activity coefficient greater than 1? |
It was recently brought to my attention that my understanding of entropy is wonky at best.
In my experience, entropy was introduced (superficially at best) during general chemistry/foundations of inorganic chem and described in terms of order/disorder of a system, usually followed by some messy room analogy. In one... |
Is it correct that a hydrogen atom only have 1 electron and 1 proton because of its molecular mass of 1 and a hydrogen ion only having no electron and 1 proton?
In an ionisation process we know that sometimes a hydrogen ion or H+ is taken out of a compound to be transferred to water, in what we know as an acid-base ... |
Am I even close to solve this problem or it is a complete disaster?
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/UY3lw.png |
I am quoting a sentence from [Non ideal solutions][1].
This source says that "if the interactions (between solute and solvent) repel each other, the activity coefficient is greater than 1. How can interactions between molecules repel each other? Don't they always line up so that the negative end is in contact with p... |
Is it correct that a hydrogen atom only has 1 electron and 1 proton since the atomic is 1?
Also, is the hydrogen ion composed of a single proton and no electrons?
In an ionisation process we know that sometimes a hydrogen ion or H+ is taken out of a compound to be transferred to water, in what we know as an acid-bas... |
Is it correct that a hydrogen atom only has 1 electron and 1 proton since the atomic mass is 1?
Also, is the hydrogen ion composed of a single proton and no electrons?
In an ionization process we know that sometimes a hydrogen ion or H+ is taken out of a compound to be transferred to water, in what we know as an a... |
I am quoting a sentence from [Non ideal solutions][1]:
> if the interactions (between solute and solvent) repel each other, the
> activity coefficient is greater than 1.
How can interactions between molecules repel each other? Don't they always line up so that the negative end is in contact with positive (and vi... |
So far I have asked this question in physics, engineering and math sections but have not gotten an answer in three years. If you have 100 identical spheres and group them into A sphere shape, how many will end up on the surface? They can be packed tight or loose in a hexagon pattern or cubicle pattern. They can be symm... |
If you accumulate 100 identical spheres how many will end up on the surface? |
Every time the precipitation on filter is washed, there is a certain constant volume $V_\mathrm{ret}$ of washing fluid retained on the filter. If the initial concentration of impurity is $c_0$, then initial amount of impurity on filter is
$$n_0 = c_0V_\mathrm{ret}$$
and after washing with a new portion of the fl... |
Every time the precipitation on filter is washed, there is a certain constant volume $V_\mathrm{ret}$ of washing fluid retained on the filter. If the initial concentration of impurity is $c_0$, then initial amount of impurity on filter is
$$n_0 = c_0V_\mathrm{ret}$$
and after washing with a new portion of the fl... |
A table of [A-values](https://en.wikipedia.org/wiki/A_value) indicate that $\ce{Br}$ substituent on a long chain organic molecule has relatively less steric effect than that of $\ce{Me}$- or $\ce{Et}$-group ($1.7$ and $\pu{1.75 kcal mol-1}$, respectively compared to $\pu{0.38 kcal mol-1}$ of $\ce{Br}$), and even smalle... |
[![enter image description here][1]][1]
I guess my main question is looking only at the Newman projection, how does one determine the stereochemistry?
In the molecule to the right, I get for the first carbon, ($\ce{Et, H, Me}$) *R* (I flipped it after moving the $\ce{H}$ back) and for $\ce{C}$2 ($\ce{Et, Br, M... |
A table of [A-values](https://en.wikipedia.org/wiki/A_value) indicate that $\ce{Br}$ substituent on a long chain organic molecule has relatively less steric effect than that of $\ce{Me}$- or $\ce{Et}$-group ($1.7$ and $\pu{1.75 kcal mol-1}$, respectively compared to $\pu{0.38 kcal mol-1}$ for $\ce{Br}$), and even small... |
>**Question 1:** Which of the following Newman projections represent the most stable confirmation of the diastereomer of the molecule given below?
>
>[![most stable confirmation of the diastereomer][1]][1]
I guess my main question is looking only at the Newman projection, how does one determine the stereochemistry... |
>Does the given compound give Lucas test?
>
>[![enter image description here][1]][1]
My teacher says due to the presence of a strong electron withdrawing group the carbocation formed is unstable.
But I say if it undergoes $\mathrm{S_N2}$ mechanism then an electron withdrawing group should increase its reac... |
In perturbation theory, if
${\hat {H}} = {\hat {H}^{(0)}} + λ{\hat {H}^{(1)}}$,
${ψ} = {ψ^{(0)}} + λ{ψ^{(1)}} +λ^2{ψ^{(2)}} + ... $ and
${E} = {E^{(0)}} + λ{E^{(1)}} +λ^2{E^{(2)}} + ... $ ,
then, by applying these three equations on ground state $ψ_0$ and using the general time-independent ${\hat {H}{ψ... |
In perturbation theory, if
\begin{align}{\hat {H}} &= {\hat {H}^{(0)}} + λ{\hat {H}^{(1)}} \tag{1}\\
{ψ} &= {ψ^{(0)}} + λ{ψ^{(1)}} +λ^2{ψ^{(2)}} + ... \tag{2}\\
{E} &= {E^{(0)}} + λ{E^{(1)}} +λ^2{E^{(2)}} + ... \tag{3}\\
\end{align}
then, by applying these three equations on ground state $ψ_0$ and using ... |
Variety of books and literature reviews consider excimer (or exciplex) emission something distinct from through-space charge transfer. Is this actually the case?
This question arises, because the more literature I read on this subject the less sure it seems to have any distinctive characteristics one from another. Mai... |
Is there an actual distinction between through-space charge transfer and excimer emission? |
Variety of books and literature reviews consider excimer (or exciplex) emission something distinct from through-space charge transfer. Is this actually the case?
This question arises, because the more literature I read on this subject the less sure it seems to have any distinctive characteristics one from another. M... |
What about a possible $\ce{F-}$ anion? While the nature of the cation might be guessed based on the flame test, since the $\ce{AgNO3}$ test gave no precipitate, it might have produced $\ce{AgF}$ (soluble in water).
This said, by looking at the densities of $\ce{M-F}$ systems with a cation with orange flame and densi... |
How do I find the total number of hyperconjugable structures in a given compound?
I read some sources stating that the total number of hyperconjugable structures is equal to the total number of alpha hydrogen. But which carbon is taken as the alpha carbon in a compound having no functional group just carbons?
[![h... |
Suppose Zn, Cd and Hg were to form a bond with the same element; say ZnCl2, CdCl2 and HgCl2 Then which of the compounds would be showing most covalent character
i feel like there are two schools of thought with regards to the covalent nature of Group 12 elements
one says according to Fajan's rule covalent charact... |
How do I find the total number of “hyperconjugable” structures for 1‐(3‐ethyl‐4‐methylphenyl)‐2‐methylpropan‐1‐ylium?
[![1‐(3‐ethyl‐4‐methylphenyl)‐2‐methylpropan‐1‐ylium][1]][1]
I read some sources stating that the total number of “hyperconjugable” structures is equal to the total number of α-hydrogen atoms. But... |
I am trying to wrap my head around transformed chemical potentials, as described in Thermodynamics of biochemical reactions (R. Alberty, 2003), however, two equations seem to be contradictory in this book.
Lets consider a chemical species $AH_n$, which has n protons. The formation reaction of that species would then... |
Your first step is incorrect. Think about it this way:
$5$ people have $10$ eyes. This group of people has $14$ eyes. How many people in the group?
The correct solution is:
This group has $14/10 = 1.4$ times more eyes than the known group. Thus, they have $1.4$ times more people. $5$ people $\cdot$($14$ eyes/... |
There is one obvious $\alpha$-position, which is the tertiary carbon atom adjacent to the carbon carrying positive charge. This contributes one hypercongujation structure. It looks like there are no more apparent structures, but the methyl group that is *para* to the cation can also participate in hyperconjugation
[... |
Your first step is incorrect. Think about it this way:
$5$ people have $10$ eyes. This group of people has $14$ eyes. How many people in the group?
The correct solution is:
This group has $14/10 = 1.4$ times more eyes than the known group. Thus, they have $1.4$ times more people. $5$ people $\cdot$($14$ eyes/... |
This question was asked in the JEE examination of 2017 :
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/RSmf7.png
[A] option is incorrect since the system is losing heat and hence $$ \Delta S\lt0$$
[B] Lets assume we have an endothermic reaction $$\ce { A <=> B - Heat} $$
N... |
I got in Paula Bruice under the section **Mechanism for Mercuric ion catalysed Hydration of Alkyne**
> Terminal alkynes are less reactive than internal alkynes towards addition of water. Hydration will take place if Hg²+ is added to acidic mixture.
Why is Terminal Alkynes less reactive than internal alkynes? |
Why is Terminal Alkynes less reactive than internal alkynes? |
I have an unknown white powder, which is an ionic solid, and I need to identify what it is by using qualitative analysis. I've run quite a few tests, but I am having a lot of trouble identifying the anion. The data I've collected is below.
**General Properties:**
- It is a white powder, and I know that it is an... |
A scene from the movie TENET made me think of a question. In the scene a gas is released into a room that is filled with precious artwork. The gas is used to rid of all oxygen in the room so fire cannot enter the facility. What kind of gas would be used to "gobble up" oxygen? Assuming there is no ventilation system to ... |
I got in Paula Bruice under the section **Mechanism for Mercuric ion catalysed Hydration of Alkyne**
> Terminal alkynes are less reactive than internal alkynes towards addition of water. Hydration will take place if Hg²+ is added to acidic mixture.
Why are Terminal Alkynes less reactive than internal alkynes? |
Why are Terminal Alkynes less reactive than internal alkynes? |
How do I find the total number of “hyperconjugable” structures for 1-(3-ethyl-4-methylphenyl)-2-methylprop-1-ylium?
[![1-(3-ethyl-4-methylphenyl)-2-methylprop-1-ylium][1]][1]
I read some sources stating that the total number of “hyperconjugable” structures is equal to the total number of α-hydrogen atoms. But ... |
Why is atomic number is more or less the same as number of neutrons for light elements? |
As we all know water is a great solvent in it's liquid form relative to other substances. I wonder however how it performs as a gas relative to other stuff.
Does anyone know how well steam carries compounds with it compared to other gases at the same temperature and pressure? |
Is steam a good "solvent"? |
Suppose Zn, Cd and Hg were to form a bond with the same element; say ZnCl2, CdCl2 and HgCl2 Then which of the compounds would be showing most covalent character
I feel like there are two schools of thought with regards to the covalent nature of group 12 elements.
One says according to Fajans' rule covalent charac... |
Thermodynamics- How are various property tables made? |
I am wondering about how the surface tension of clean soapy water changes as oil is added to it? Is the change gradual or is it abrupt as the amount of oil added exceeds the amount of soap available to surround the oil. So if the surface tension of clean soapy water is 25 dynes/cm, then as I add oil, will that surfac... |
I'm adding this answer as maybe reasoning of why IUPAC might chose to put the charge symbol after the number. Consider it a suppliment to the @fred-senese's answer of *'cause IUPAC says so*, and the linked article.
We put the charge symbol (+ or -) after the number because charges are entities, not numbers. Placing ... |
I'm adding this answer as maybe reasoning of why IUPAC proposed putting the charge symbol after the number. Consider it a supplement to the @fred-senese's answer of *'cause IUPAC says so*, and the linked article.
We put the charge symbol (+ or -) after the number because charges are entities, not numbers. Placing th... |
Take molecules A and B below. In A, we can move the electrons from the green pi bond into a lone pair on oxygen, then move the blue lone pair of electrons from the other oxygen to form a new pi bond, and this is a valid resonance structure. But in B, I was told that if we move the electrons in the green pi bond into a ... |
When does replacing a double bond with a lone pair result in a valid resonance structure? |
Hydrogen peroxide decomposes at room temperature and so I was wondering what temperature is sufficient for this decomposition to occur.
Can someone explain how we can determine this? (theoretically or experimentally - but to me it seems like it would be easier to determine experimentally)
I don't know if there is ... |
How would one determine the temperature needed such that hydrogen peroxide will start to decompose? |
The question can be reformulated to:
"At what T is the equation $\exp{\left(-\frac{E}{RT}\right)}=0$ true ?"
Ther is no temperature above which $\ce{H2O2}$ decomposes and below which it does not. It is rather about an arbitrary choice of acceptable decomposition rate.
It is at very low temperatures kinetically stab... |
Suppose $\ce{Zn}$, $\ce{Cd}$ and $\ce{Hg}$ were to form a bond with the same element; say $\ce{ZnCl2}$, $\ce{CdCl2}$ and $\ce{HgCl2}$ Then which of the compounds would be showing most covalent character
I feel like there are two schools of thought with regards to the covalent nature of group 12 elements.
One says... |
The question can be reformulated to:
"At what T is the equation $\exp{\left(-\frac{E}{RT}\right)}=0$ true ?"
Ther is no temperature above which $\ce{H2O2}$ decomposes and below which it does not. It is rather about an arbitrary choice of acceptable decomposition rate.
It is similar to solvent evaporation. There is n... |
The question can be reformulated to:
"At what T is the equation $\exp{\left(-\frac{E}{RT}\right)}=0$ true ?"
There is no temperature above which $\ce{H2O2}$ decomposes and below which it does not. It is rather about an arbitrary choice of acceptable decomposition rate.
It is similar to solvent evaporation. There is ... |
The question can be reformulated to:
"At what T is the equation $\exp{\left(-\frac{E}{RT}\right)}=0$ true ?"
There is no temperature above which $\ce{H2O2}$ decomposes and below which it does not. It is rather about an arbitrary choice of acceptable decomposition rate.
It is similar to solvent evaporation. There is ... |
> A crystal is made up of atoms X, Y, and Z. Atoms X are in FCC packing, Y occupy all octahedral voids and Z occupies all the tetrahedral voids. If all the atoms along two body diagonal are removed, find formula of crystal.
Since there are 4 atoms in FCC, number of X=4. Tetrahedral voids occupy twice the number of a... |
Where are the tetrahedral voids and octahedral voids located in an FCC? |
I am trying to wrap my head around transformed chemical potentials, as described in Thermodynamics of biochemical reactions (R. Alberty, 2003), however, two equations seem to be contradictory in this book.
Lets consider a chemical species $AH_n$, which has n protons. The formation reaction of that species would then... |
Take molecules A and B below. In A, we can move the electrons from the green pi bond into a lone pair on oxygen, then move the blue lone pair of electrons from the other oxygen to form a new π bond, and this is a valid resonance structure. But in B, I was told that if we move the electrons in the green π bond int... |
When a ionic compound like NaCl dissolves, it doesnt always full dissociate due to ionic pairing. This is measured by the van't hoff factor. Now, this is what I'm looking at for my chem experiment - how does ionic pairing affect freezing point depression. With changing radius... the ionic pairing should change, and hen... |
In what solvents does ionic association occur? |
I am trying to wrap my head around transformed chemical potentials, as described in Thermodynamics of biochemical reactions (R. Alberty, 2003), however, two equations seem to be contradictory in this book.
Lets consider a chemical species $AH_n$, which has n protons. The formation reaction of that species would then... |
When a ionic compound like NaCl dissolves, it doesnt always full dissociate due to ionic pairing. This is measured by the van't hoff factor. Now, this is what I'm looking at for my chem experiment - how does ionic pairing affect freezing point depression. With changing radius... the ionic pairing should change, and hen... |
Nuclear fusion within stars combine atom nuclei, so the atoms are ionized and electrons run for free.
My question is, when or how these electrons recombine with the nuclei to form neutral atoms? inside the star? outside? |
When a ionic compound like $\ce{NaCl}$ dissolves, it doesn't always full dissociate due to ionic pairing. This is measured by the van 't Hoff factor. Now, this is what I'm looking at for my chem experiment - how does ionic pairing affect freezing point depression. With changing radius the ionic pairing should change, a... |
I came across a question, predict the major product when conc.NaOH is added to a mixture of PhCHO and HCHO.
According to me, as HCHO is less hindered and C=O of HCHO is more reactive, so the major products must be CH2ONa and HCOONa. The hydride transfer should be from one Formaldehyde molecule to the other.
Howev... |
I came across a question:
>Predict the major product when conc. $\ce{NaOH}$ is added to a mixture of $\ce{PhCHO}$ and $\ce{HCHO}$.
According to me, as $\ce{HCHO}$ is less hindered and $\ce{>C=O}$ of $\ce{HCHO}$ is more reactive, so the major products must be $\ce{CH2ONa}$ and $\ce{HCOONa}$. The hydride transfer sho... |
Litmus Papers are used to test acidity and alkalinity of a fluid. Are there other paper-based tools to test for other stuff like dissolved oxygen, presence of toxicity, radioactivity etc? |
Litmus papers are used to test acidity and alkalinity of a fluid. Are there other paper-based tools to test for other stuff like dissolved oxygen, presence of toxicity, electric potential etc? |
I successfully found 2, but the answer key says that there are 4 such compounds possible. I found:
- 3-methyl hexane
- 2,3-dimethyl pentane
We can't have a cyclic ring as the masses won't match. What else could be made folks? |
How many alkanes having a molecular weight of hundred, are chiral? |
In our chemical bonding class we were given the following problem:
>[![Problem][1]][1]
I am confused by how the question says that you need to consider the heat of vaporization/sublimation for HBr and HI.
>Bond dissociation enthalpy is defined as "the energy needed to break one mole of the bond to give sepa... |
Are all gases equal in their ability to carry with them lower volatility matter at a given temperature? |
I came across a question:
>Predict the major product when conc. $\ce{NaOH}$ is added to a mixture of $\ce{PhCHO}$ and $\ce{HCHO}$.
According to me, as $\ce{HCHO}$ is less hindered and $\ce{>C=O}$ of $\ce{HCHO}$ is more reactive, so the major products must be $\ce{CH3ONa}$ and $\ce{HCOONa}$. The hydride transfer sho... |
To me it makes sense that the activation energy $E_a$, as given by the Arrhenius equation, doesn't depend on the temperature as the needed energy (potential energy) to start a reaction has nothing to do with the temperature (kinetic energy) of the molecules. And a higher temperature simply means that more molecules hav... |
Why does activation energy depend on temperature? |
If I have Oxygen Gas and Ozone together would it be considered a pure substance or a mixture?
$$O_2 + O_3$$ |
Would Oxygen Gas and Ozone be a pure substance together? |
If I have Oxygen Gas and Ozone together would it be considered a pure substance or a mixture?
$$O_2 + O_3$$
And would pure substances always have the same molecular structure? |
If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? |
Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a [Wikipedia definition on substances](https://en.wikipedia.or... |
Consider this typical 1,2 methanide shift in a carbocation:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/JUX6p.png
Which isotopic form of methanide ($\ce{CH3, CD3, or CT3}$) would migrate from secondary carbocation to form more stable tertiary carbocation?
[This](https://link.s... |
To me it makes sense that the activation energy $E_\mathrm a$, as given by the Arrhenius equation, doesn't depend on the temperature as the needed energy (potential energy) to start a reaction has nothing to do with the temperature (kinetic energy) of the molecules. And a higher temperature simply means that more molec... |
You need to prepare 250.0 mL of an aqueous solution of ethanol in the concentration will be 0.500 mol / L. You have 100 mL of a commercial solution of ethanol in water (35.0% v / v) available. The density of ethanol (pure) under these conditions is 0.7893 g / mL and that of water is 0.9970 g / mL.
1.What volume (in ... |
You need to prepare 250.0 mL of an aqueous solution of ethanol in the concentration will be 0.500 mol / L. You have 100 mL of a commercial solution of ethanol in water (35.0% v / v) available. The density of ethanol (pure) under these conditions is 0.7893 g / mL and that of water is 0.9970 g / mL.
1.What volume (in ... |
Resistant starch, as found in potato starch, is supposed to have [health benefits](https://www.healthline.com/nutrition/resistant-starch-101). There are differing opinions on whether or not heating potato starch destroys the resistant starch in it and thereby also the supposed health benefits. I would like to know what... |
Does heating potato starch destroy its resistant starch? |
I want to remove acetic acid from a mixture of acetic acid and water by aeration. The concentration of acetic acid is 200 ppm (mg/L). The pH of the water is more than 5. I want to reduce the acetic acid concentration by around 80%.
I understand that acetic acid can be removed by addition of sulphuric acid to bring do... |
How to make acetic acid more volatile so that it can be removed by vigorous aeration of an acetic acid-water mixture? |
You need to prepare 250.0 mL of an aqueous solution of ethanol in the concentration will be 0.500 mol / L. You have 100 mL of a commercial solution of ethanol in water (35.0% v / v) available. The density of ethanol (pure) under these conditions is 0.7893 g / mL and that of water is 0.9970 g / mL.
1.What volume (in ... |
>You need to prepare $\pu{250.0 mL}$ of an aqueous solution of ethanol in the concentration will be $\pu{0.500 mol L-1}$. You have $\pu{100 mL}$ of a commercial solution of ethanol in water $(35.0\% \,V/V)$ available. The density of ethanol (pure) under these conditions is $\pu{0.7893 g mL-1}$ and that of water is $\pu... |
Consider this typical 1,2 methanide shift in a carbocation:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/JUX6p.png
Which isotopic form of methanide ($\ce{CH3, CD3, or CT3}$) would migrate from secondary carbocation to form more stable tertiary carbocation?
[This](https://link.s... |
Sulfuric acid, $\ce{H2SO4}$, having an enthalpy of formation of $-814\ \mathrm{kJ/mol}$, is quite stable and won't decompose easily.
According to [*A Kinetic Study of the Decomposition of Spent Sulfuric Acids at High Temperature, Dominique Schwartz, Roger Gadiou, Jean-François Brilhac, Gilles Prado, and Ginès Martin... |
How would $\ce{H2SO4}$ react to heat? I assume that it would form toxic sulfur (di/tri)oxide, but I can't find any information on this.
I'm concerned about fire hazards specifically, so assume very intense heating and very low concentration. |
What are the fragments that result from taking the Mass Spectrum of o-fluronitrobenzene? |
So far I have asked this question in physics, engineering and math sections but have not gotten an answer in three years. If you have 100 identical spheres and group them into A sphere shape, how many will end up on the surface? They can be packed tight or loose in a hexagon pattern or cubicle pattern. They can be symm... |
So far I have asked this question in physics, engineering and math sections but have not gotten an answer in three years. If you have 100 identical spheres and group them into A sphere shape, how many will end up on the surface? They can be packed tight or loose in a hexagon pattern or cubicle pattern. They can be symm... |
Resistant starch, as found in potato starch, is supposed to have [health benefits](https://www.healthline.com/nutrition/resistant-starch-101). There are differing opinions on whether or not heating potato starch destroys the resistant starch in it and thereby also the supposed health benefits. I would like to know what... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/39T8D.jpg
I know that there is something to do with the vapour pressure of pure water being higher than the vapour pressure of the sugar solution, but I still can’t really explain what happens on a molecular level. Could someone help? |
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