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Does the third law of thermodynamics apply to all compounds and elements? |
I dont know if this is really applicable but I want to add a custom force ( say F(x,y,z) ) to some atoms in my geometry optimization. Is there any way to add such forces to the DFT calculation? ( preferably GAMESS or Gaussian)
Let me bring an example. Say I have molecule A and molecule B and a force that changes in ... |
K$_a$ values for Brønsted-Lowry acids are easy to find, but not so much for Lewis acids. I need to calculate the theoretical pH in a 50 mL water solution where 6.4E-4 g of Ca$^{2+}$ is present. The reaction I base this on is the following
$$
\ce{Ca^{2+}(aq) + 2H2O (l) \rightleftarrows Ca(OH)2 (s) + 2H^+ (aq)}
$$
... |
I dont know if this is really applicable but I want to add a custom force ( say F(x,y,z) ) to some atoms in my geometry optimization. Is there any way to add such forces to the DFT calculation? ( preferably GAMESS or Gaussian). It can be also done as Molecular Mechanics (**MM**) as I just need an approximate geometry ... |
According to wikipedia, the third law of thermodynamics is "The entropy of a perfect crystal, at absolute zero (zero kelvins), is exactly equal to zero.".
Then, theoretically, could all substances, including molecular compounds, attain absolute zero? Another way of thinking of this question is whether all compounds ... |
K$_a$ values for Brønsted-Lowry acids are easy to find, but not so much for Lewis acids. I need to calculate the theoretical pH in a 50 mL water solution where 6.4E-4 g of Ca$^{2+}$ is present. The reaction I base this on is the following
$$
\ce{Ca^{2+}(aq) + 2H2O (l) \rightleftarrows Ca(OH)2 (s) + 2H^+ (aq)}
$$
... |
$K_\text{a}$ values for Brønsted-Lowry acids are easy to find, but not so much for Lewis acids. I need to calculate the theoretical pH in a 50 mL water solution where 6.4E−4 g of $\ce{Ca^2+}$ is present. The reaction I base this on is the following
$$
\ce{Ca^2+(aq) + 2H2O(l) <=> Ca(OH)2(s) + 2H+(aq)}
$$
$$
K_\... |
$K_\mathrm{a}$ values for Brønsted-Lowry acids are easy to find, but not so much for Lewis acids. I need to calculate the theoretical $\mathrm{pH}$ in a $50~\mathrm{mL}$ water solution where $6.4\times10^{-4}~\mathrm{g}$ of $\ce{Ca^{2+}}$ is present. The reaction I base this on is the following
$$
\ce{Ca^{2+}_{(aq)... |
$K_\mathrm{a}$ values for Brønsted-Lowry acids are easy to find, but not so much for Lewis acids. I need to calculate the theoretical $\mathrm{pH}$ in a $50~\mathrm{mL}$ water solution where $6.4\times10^{-4}~\mathrm{g}$ of $\ce{Ca^{2+}}$ is present. The reaction I base this on is the following
$$
\ce{Ca^{2+}_{(aq)... |
You're confusing terms here. $\ce{K_{a}}$ is the (Bronsted) acid dissociation constant. This suggests that $\ce{K_a}$ refers to the degree that a **Bronsted** acid dissociates into its conjugate base and hydrogen protons.
$\ce{K_{a}}$ is inapplicable to Lewis acids because Lewis acids are *not* proton donors.
B... |
I need to calculate the theoretical $\mathrm{pH}$ in a $50~\mathrm{mL}$ water solution where $6.4\times10^{-4}~\mathrm{g}$ of $\ce{Ca^{2+}}$ is present. The reaction I base this on is the following
$$
\ce{Ca^{2+}_{(aq)} + 2H2O_{(l)} \rightleftarrows Ca(OH)2_{(s)} + 2H^+_{(aq)}}
$$
$$
K = \frac{[\ce{H+}]^2}{[\c... |
Does the relationship equation between standard cell potential and equilibrium constant violate potential's intensive properties? |
The problem asks to determine the $[\ce{H+}]$ in a $0.20~\mathrm{M}$ solution of $\ce{Na3PO4}$. The $K_\mathrm{a}$ of $\ce{HPO4-}$ was given as $4.5\times 10^{-13}$, which then allows one to calculate the corresponding $K_\mathrm{b}$ as $2.22\times10^{-2}$.
As any acid-base problem, I simply set up the expression $\... |
No, not always.
For example, in the classic Galvanic cell: ![enter image description here][1]
[1]: https://i.stack.imgur.com/W9DBC.gif
In the above image, you have zinc metal acting as a reducing agent at the anode, true to your line of thinking. However, it is also the case that the copper ions at the cat... |
I'm stuck on a particular problem which I can't work my head around:
Information has been given that :The boiling point of benzene at atmospheric pressure is 353 K and the enthalpy of vaporization of benzene is 30.8 kJ mol–1 at this temperature. The molar heat capacities of the liquid and vapour are 136.1 and 81.7 J... |
How can I work out the entropy change of benzene when it changes from vapour into liquid? |
I'm stuck on a particular problem which I can't work my head around:
Information has been given that :The boiling point of benzene at atmospheric pressure is 353 K and the enthalpy of vaporization of benzene is 30.8 kJ mol<sup>–1</sup> at this temperature. The molar heat capacities of the liquid and vapour are 136.1... |
How to calculate the required concentration for sodium sulfite to remove oxygen as an oxygen scavenger from a solution? |
If I know the amount of oxygen in such a solution, how can I know the required concentration of sodium sulfite to be used and react as oxygen scavenger? |
So while calculating for the relative yield of monochlorination for 2,3-dimethylbutane, I was counting the primary hydrogens, I counted 6, but in fact it was 12. Why is it 12? How do you find equivalent hydrogens? Since the compound is symmetrical doesn't the hydrogens on both sides be equivalent to each other? ![ente... |
I'm really new to chemistry and need to determine what percent of a solution needs to be acetic acid for a particular pH. I've had a look around but can't quite figure it out. I have 100% acetic acid, and want a pH of 5. Can anyone help me with how to do this? (Say for a volume of 1L). |
This is a dilution problem. So in this instance, you want to add deionized water to your acetic acid. However, the question is, how much water do you add?
It is necessary first to find the molarity of the acetic acid. On [PubChem][1], we see that the molecular weight is $60.05196 \ \frac{\text{g}}{\text{mol}}$ and d... |
Here it says that the hydrocarbon tail is non-polar. I understand that the H on top of the C and on the bottom have dipoles that cancel, but at the very end, with the CH3 group, there is no opposing v... |
Why is a hydrocarbon tail non-polar? |
Here it says that the hydrocarbon tail is non-polar. I understand that the H on top of the C and on the bottom have dipoles that cancel, but at the very end, with the $\ce{CH3}$ group, there is no opp... |
Here it says that the hydrocarbon tail is non-polar. I understand that the $\ce{H}$ on top of the $\ce{C}$ and on the bottom have dipoles that cancel, but at the very end, with the $\ce{CH3}$ group, t... |
I notice when using SMILES or a IUPAC name for many molecules and generating them in Chembio3D, and then running MM2 > Minimize Energy, the structures produced are most of the time not reflections of any conformation observed physiologically.
I'm wondering if there's a way I can import protein and other macromolecu... |
My understanding says **organo-metallic** = organic + metallic compunds. One already known to me is **Grignard Reagent** (RMgX). But would you consider NaOMe or NaCCH as an **organometallic compound**? Would you consider LiOAc, LiOMe, LiN(Me)Me or LiMe? |
Are these organo-metallic compounds? |
What percent of a solution needs to be acetic acid for a particular $\mathrm{pH}$? I have 100% acetic acid, and want $1~\mathrm{L}$ of solution with a $\mathrm{pH}$ of 5. I've done some research, but I still do not understand how to solve this problem. |
Reaction with Silver Oxalate? |
I have a solution containing 0.2 moles of $\ce{Br^-}$ ions and $\ce{SO_4^2-}$ ions each.
Now if I add excess $\ce{AgNO3}$ in this solution,
what will precipitate?
$\ce{Ag2SO4}$ or $\ce{AgBr}$ or both?
And if I add just 0.2 moles of $\ce{AgNO3}$, what will precipitate? |
What precipitates? |
> What percent of a solution needs to be acetic acid for a particular pH? I have 100% acetic acid, and want 1 L of solution with a pH of 5. I've done some research, but I still do not understand how to solve this problem.
You need to know that if you add water moles remian same so $\rm M_1V_1=M_2V_2$. You also need ... |
I have a solution containing 0.2 moles of $\ce{Br^-}$ ions and $\ce{SO_4^2-}$ ions each.
Now if I add excess $\ce{AgNO3}$ in this solution,
what will precipitate?
$\ce{Ag2SO4}$ or $\ce{AgBr}$ or both?
And if I add just 0.2 moles of $\ce{AgNO3}$, what will precipitate?
(I don't want ... |
To my understanding, only $\ce{NaC#CH}$ and $\ce{LiCH3}$ are organometallic compounds.
According to the [**IUPAC** definition of organometallic compounds](http://www.iupac.org/nc/home/publications/provisional-recommendations/published/published-container/nomenclature-of-organometallic-compounds-of-the-transition-ele... |
My understanding says **organo-metallic** = organic + metallic compunds.
One already known to me is **Grignard Reagent** ($\ce{RMgX}$).
But would you consider $\ce{NaOMe}$ or $\ce{NaCCH}$ as an **organometallic compound**? Would you consider $\ce{LiOAc}$, $\ce{LiOMe}$, $\ce{LiN(Me)2}$ or $\ce{LiMe}$? |
> I cannot decide whether the H in the aldehyde group would be split into a doublet or remain as a singlet […]
What would be the argument **against** $^3J$ coupling between these protons? The aldehyde proton will appear as a doublet.
Don't forget that coupling works both ways! $\ce{(CH3)2C\color\red{H}-}... |
This is a dilution problem. So in this instance, you want to add deionized water to your acetic acid. However, the question is, how much water do you add?
It is necessary first to find the molarity of the acetic acid. On [PubChem][1], we see that the molecular weight is $60.05196 \ \frac{\text{g}}{\text{mol}}$ and d... |
As a contact lenses user, I was looking for information about which polymers are more healthy for contact lenses. Ionic or non-ionic?
It's very hard to find credible and non-biased info about contact lenses on the internet so I remembered to ask here.
Edit:
Normally I use Biomedics 55 (Ocufilcon D - ionic) or So... |
Which polymers are healthier for contact lenses? Ionic or non ionic? |
Is it possible to melt diamonds into a liquid? I mean if you heat diamond at open air it will start to burn around 700 degree celsius, reacting with oxygen to produce carbon dioxide gas. In the absence of oxygen it will transform into graphite, a more stable form of carbon, long before turning into graphite. My questio... |
My understanding says **organo-metallic** = organic + metallic compunds. One already known to me is **Grignard Reagent** (RMgX). But would you consider NaOMe or NaCCH as an **organometallic compound**? Would you consider LiOAc, LiOMe, LiN(Me)Me or LiMe? |
My understanding says **organo-metallic** = organic + metallic compunds.
One already known to me is **Grignard Reagent** ($\ce{RMgX}$).
But would you consider $\ce{NaOMe}$ or $\ce{NaCCH}$ as an **organometallic compound**? Would you consider $\ce{LiOAc}$, $\ce{LiOMe}$, $\ce{LiN(Me)2}$ or $\ce{LiMe}$? |
As you can see the atom consists not only of the nucleus and electron but also of "empty space is the space empty or is their something else?![enter image description here][1]
[1]: https://i.stack.imgur.com/6oOwF.png |
What is there in an atom between the nucleus and electrons? |
Could someone please show me the MO diagram for $\ce{N_2^{2-}}$? What I did was since N has 5 valence $\ce{e^{-}}$, then $\ce{N_2}$ must have 10, and $\ce{N_2^{2-}}$ must have 12. And $\ce{N}$ has $s$ and $p$ orbital mixing. So when I draw out the MO it has all the orbitals filled. And the bond order is $\frac{1}{2}(6-... |
Is there an algorithm for finding the number of cyclic isomers a given compound might have?
I've found a general algorithm for all isomers: [link](http://www-jmg.ch.cam.ac.uk/data/isomercount/isojava.html), but I'm not sure how to apply it for cyclic isomers only. |
A) Symmetric $\ce{CO2}$ stretch.
A particular vibrational mode is considered IR active, if there is a change of *transition dipole moment*. $\ce{CO2}$ is linear, and the symmetric stretching mode means both oxygens move in/outward concurrently.
You can see an illustration of the symmetric and antisymmetric stretchi... |
I have to decide which one has a higher oxidation strength $\ce{ClO-}$ or $\ce{Cl2}$
$\ce{ClO- + H2O + 2e- -> Cl- + 2OH-}$
$\ce{Cl2 + 2e- -> 2Cl-}$
Will this reaction occur?
$\ce{ClO- + H2O + 2Cl- -> Cl- + 2OH- + Cl2}$
In my opinion not, because otherwise the $\ce{ClO-}$ is reduced to $\ce{Cl-}$. If the ... |
Which substance has the higher oxidation strength? |
Is it possible to melt diamonds into a liquid? I mean if you heat diamond at open air it will start to burn around 700 degrees Celsius, reacting with oxygen to produce carbon dioxide gas. In the absence of oxygen it will transform into graphite, a more stable form of carbon, long before turning into graphite. My questi... |
1. what are the answer for CONFIRMATION OF REGISTRATION when register in dalton forum ?
2. install got error, how to install dalton 2015
wonder@wonder-VirtualBox:~/dalton/DALTON-Source$ uname -r
3.8.0-29-generic
wonder@wonder-VirtualBox:~/dalton/DALTON-Source$ sudo apt-get install openmpi-... |
One of my exam questions is about lipstick and calculating the amount of lithium in the lipstick by AAS. The determination took place by making standard solutions with known concentrations of lithium. For the stock solution 653,3mg lithiumchloride, LiCl, was dissolved in 100ml.
MW(lithium) = 6,49 g/mol
MW(LiCl) = ... |
Can someone verify my calculation? |
I’m dealing with electrochemistry problems.
For the following reaction
$$\ce{2H+ +2e- <=>H2}\quad E^\circ=0\ \mathrm{V}$$
Does it make sense to say
$$\Delta G^\circ=-nFE^\circ=0$$
Which would mean the reaction is in equilibrium?
|
In all of my physical chemistry books I find the same expression for estimating the equilibrium constant of a reaction at a non-standard temperature. The derivation starts with $R \ln K_\text{eq} = -\Delta g^\circ/T = -(\Delta h^\circ/T - \Delta s^\circ)$. Then one takes the temperature derivative of each side assuming... |
The Inter molecular interaction that is dependent on the inverse cube of distance between the molecules is:
1. Hydrogen Bond
2. ion-ion interaction
3. ion-dipole interaction
4. London Force
My thinking:
> inverse cube of distance i thought means that it is ion-dipole interaction. since we know force due ... |
One of my exam questions is about lipstick and calculating the amount of lithium in the lipstick by AAS. The determination took place by making standard solutions with known concentrations of lithium. For the stock solution **653,3mg lithiumchloride, LiCl, was dissolved in 100ml.**
MW(lithium) = 6,49 g/mol
MW(LiCl... |
March's Advanced organic chemistry has the following paragraph -
>The other effect operates not
>through bonds, but directly through space or solvent molecules, and is called the field
>effect. It is often very difficult to separate the two kinds of effect, but it has been
done in a number of cases, generally by... |
1. what are the answer for CONFIRMATION OF REGISTRATION when register in dalton forum ?
2. install got error, how to install dalton 2015
<!-- language: lang-js -->
wonder@wonder-VirtualBox:~/dalton/DALTON-Source$ uname -r
3.8.0-29-generic
wonder@wonder-VirtualBox:~/dalton/DALTON-Source$ sud... |
One of my exam questions is about lipstick and calculating the amount of lithium in the lipstick by AAS. The determination took place by making standard solutions with known concentrations of lithium. For the stock solution **653,3mg lithiumchloride, LiCl, was dissolved in 100ml.**
MW(lithium) = 6,49 g/mol
MW(LiCl... |
As pointed out by Wildcat have a look at these messages:
`CMake Error at /usr/share/cmake-2.8/Modules/CMakeTestFortranCompiler.cmake:40 (MESSAGE): The Fortran compiler "/usr/bin/mpif90" is not able to compile a simple test program.`
and
`The Open MPI wrapper compiler was unable to find the specified compi... |
I mean by "combining" making a new half equation. Not a overall equation.
One that cannot be made by combining:
$MnO_2(s) + 4H^+(aq) + 2e^- \rightarrow Mn^{2+}(aq) + 2H_2O(l)$ $E^。= 1.23V$
I was trying to combine these two but couldn't get the same same potential by adding:
$MnO_4^-(aq) + 4H^+(aq) + 5e^- \righta... |
Why some redox half-equations can be combined and some not? |
This is a dilution problem. So in this instance, you want to add deionized water to your acetic acid. However, the question is, how much water do you add?
It is necessary first to find the molarity of the acetic acid. On [PubChem][1], we see that the molecular weight is $60.05196 \ \frac{\text{g}}{\text{mol}}$ and d... |
I mean by "combining" making a new half equation. Not a overall equation.
One that cannot be made by combining:
$\ce{MnO2(s) + 4H+(aq) + 2e- -> Mn^{2+}(aq) + 2H2O(l)}\quad E^\circ= 1.23\,\mathrm{V}$
I was trying to combine these two but couldn't get the same same potential by adding:
$\ce{MnO4^{-}(aq) + 4H^... |
One of my exam questions is about lipstick and calculating the amount of lithium in the lipstick by AAS. The determination took place by making standard solutions with known concentrations of lithium. For the stock solution **653.3mg lithiumchloride, LiCl, was dissolved in 100ml.**
MW(lithium) = 6.49 g/mol
MW(LiCl... |
The Inter molecular interaction that is dependent on the inverse cube of distance between the molecules is:
1. Hydrogen Bond
2. ion-ion interaction
3. ion-dipole interaction
4. London Force
My thinking:
Inverse cube of distance I think means that it is ion-dipole interaction. since we know force due to a... |
I’m stuck on a particular problem which I can’t work my head around:
Information has been given that: The boiling point of benzene at atmospheric pressure is 353 K and the enthalpy of vaporization of benzene is 30.8 kJ mol<sup>−1</sup> at this temperature. The molar heat capacities of the liquid and vapour are 136.1... |
March's Advanced Organic Chemistry has the following paragraph -
>The other effect operates not
>through bonds, but directly through space or solvent molecules, and is called the field
>effect. It is often very difficult to separate the two kinds of effect, but it has been
done in a number of cases, generally by... |
Why is -I effect of the isotopes of Hydrogen in the order
T>D>H ?
Google has nothing to offer.
Does it have to do anything with mass ?
(as the order implies) |
Why is +I effect of the isotopes of Hydrogen in the order
T>D>H ?
Google has nothing to offer.
Does it have to do anything with mass ?
(as the order implies) |
C2H5+ vs C3H7+
There are two conflicting trends here.
Inductive effect of ethyl will be higher than that of methyl so carbocation attached to ethyl (so 3 carbons in total) should be more stable.
On the other hand 3 hyperconjugation structures can be drawn for the carbocation attached to methyl ( 2 carbons in tot... |
Which carbocation is more stable , the one attached to methyl or the one attached to ethyl? |
$\ce{C2H5+ vs \ C3H7+}$
There are two conflicting trends here.
Inductive effect of ethyl will be higher than that of methyl so carbocation attached to ethyl (so 3 carbons in total) should be more stable.
On the other hand 3 hyperconjugation structures can be drawn for the carbocation attached to methyl ( 2 carbo... |
How can I balance this equation atomically and electrically? $$\ce{C2O4^2- + MnO2 -> Mn^2+ + CO2}$$ |
How can I balance the following equation atomically and electrically? |
In a container with volume 4 litres we have 2 moles $\ce{COCl2}$ and 4 moles $\ce{Cl2}$. Equilibrium is achieved when 60 % of the reactant $\ce{COCl2}$ is wasted 60 %. What is the equilibrium constant $\ce{CO + Cl2 <=> COCl2}$?
In my book it is explained the solution. I understand it when it says that $\ce{PCl5}$ is... |
$\ce{C2H5+ vs \ C3H7+}$
There are two conflicting trends here.
Inductive effect of ethyl will be higher than that of methyl so carbocation attached to ethyl ( 3 carbons in total) should be more stable.
On the other hand 3 hyperconjugation structures can be drawn for the carbocation attached to methyl ( 2 carbons... |
I am working on a project for my General Chemistry class.
I am trying to compare the EtOH production (and the rate of EtOH production) between seven types of yeast strains by fermenting the YPD media, apple juice, or both, if necessary. I can describe the difference between the yeast strains if asked, but I don't th... |
In electrolysis, does it make any difference if the electrolyte is an molten, aqueous or dilute aqueous solution? |
I dont know if this is really applicable but I want to add a custom force ( say F(x,y,z) ) to some atoms in my geometry optimization. Is there any way to add such forces to the DFT or Molecular Mechanics calculations? ( preferably GAMESS or Gaussian).
**It can be also done as Molecular Mechanics (MM)** as I just ne... |
I dont know if this is really applicable but I want to add a custom force ( say F(x,y,z) ) to some atoms in my geometry optimization. Is there any way to add such forces to the DFT or Molecular Mechanics calculations? ( preferably GAMESS or Gaussian for QC or Avogadro for MM ).
**It can be also done as Molecular Me... |
Thank you for an especially clear and detailed question!
> For YPD + apple juice fermentation, I was thinking of doing the same procedure with 50 mL YPD + 50 mL apple juice in each "special flask". Will this work?
I think this would work but it seems like a better comparison to your earlier experiments to keep u... |
is it possible for n to ever be negative? Trying to figure out where I went wrong on some thing and want to rule that out. |
n in /\G = -nFE, ever negative? |
You already determined the $\Delta S$ for benzene at 353 by dividing the $\Delta H$ at 353 by the temperature 353. Now all you need to do is determine the $\Delta H$ at 343 using Hess' law? Once you do that, you can get the $\Delta S$ at 343. |
I thought that the ratio of silicon to oxygen in a silica tetrahedron was 1:4, so if a single chain is just many of these linked together, why does the ratio become 1:3? |
Why is the ratio between Silicon and Oxygen 1:3 in single chain silicates? |
Is it possible for n to ever be negative? Trying to figure out where I went wrong on some thing and want to rule that out. |
n in Delta G = -nFE, ever negative? |
In Wurtz reaction, is the intermediate formed a carbanion or a free radical. And if can assume both mechanisms to be true, how can we decide the reacitivity of a tertiary halide? |
Does Wurtz reaction follow an ionic mechanism or a free radical mechanism? |
According to Wikipedia:
> Also, since the reaction involves free radical species, a side reaction occurs to produce an alkene. This side-reaction becomes more significant when the alkyl halides are bulky at the halogen-attached carbon.
How would a radical reaction end up producing an alkene in the context of the... |
Okay, so I'm confused, how do you get from 2,3-dimethylcyclopentanol to 1,2-dimethylcyclopent-1-ene via acid (concentrated sulphuric acid and heat in this case) catalyzed dehydration? I know the -OH group leaves as water (being protonated by acid) forming a carbocation. Then the weak nucleophile (water) attacks the bet... |
How do you get from 2,3-dimethylcyclopentanol to 1,2-dimethylcyclopent-1-ene?
I know the -OH group leaves as water (being protonated by acid) forming a carbocation. Then the weak nucleophile (water) attacks the beta-hydrogen to form what I think is 2,3-dimethylcyclopent-1-ene. But why is it 1,2-dimethylcyclopent-1-... |
It is stated in my book "All gases condense to form liquids or solids before -273.15 degree Celsius is reached?
could you explain this statement generally and my question in the title specifically? |
How can cooling gases do not change their physical states? |
One of my exam questions is about lipstick and calculating the amount of lithium in the lipstick by AAS. The determination took place by making standard solutions with known concentrations of lithium. For the stock solution **653.3mg lithiumchloride, LiCl, was dissolved in 100ml.**
> MW(lithium) = 6.49 g/mol MW(LiC... |
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