All Questions
11
questions
6
votes
1
answer
237
views
Non-Arrhenius temperature dependence of bimolecular reaction rates at very high temperatures
Once I have read that in some cases bimolecular reactions can exhibit a maximum as a function of temperature due to the short lifetime of the activated complex at very high temperatures.
At low ...
- 163
2
votes
0
answers
84
views
Diffusion vs mobility and the Einstein relation
This former question is about the mobility constant $M>0$ in the Cahn-Hilliard equation. To determine the value of such a mobility for a simulation study, Kim and Sanders (2020)
use the formula
$$
...
- 193
1
vote
0
answers
55
views
Why probability for an atom is fraction for population?
In the canonical ensemble the probability of finding an atom (or molecule) in its $i$-th energy state is given by the Boltzmann factor.
This probability is interpreted as the number of microstates ...
- 766
3
votes
0
answers
21
views
Correlating specific heat (Cp) of a substance with other substance on the basis of similar physio-chemical properties
I am modelling $\ce{H2O2}$ decomposition in ANSYS Chemkin-Pro and I have difficulty finding $C_p$ (specific heat at constant pressure) for liquid $\ce{H2O2}$ for various temperature ranges.
My ...
- 31
2
votes
0
answers
32
views
expression of apparent reaction quotient
question
When computing the Gibbs energy change of a reaction using Legendre-transformed $\Delta_fG'$ values for a given $\mathrm{pH}$, the formula of the $\Delta_rG'$ of the reaction is:
$\Delta_rG' ...
- 306
1
vote
2
answers
227
views
Concept of enthalpy at a given temperature
In thermodynamics, we always quote a fixed temperature, whenever we mention enthalpy of a reaction. For instance, one can determine the enthalpy of combustion of methane at 25 °C. Now almost all ...
- 41.6k
2
votes
0
answers
99
views
Why is it impossible to liquefy a gas with only pressure? [duplicate]
Why is it impossible to turn it to liquid by using only pressure after it reaches critical temperature? What happens in the molecular level? If we put enough pressure, the molecules are supposed to ...
- 307
4
votes
1
answer
208
views
Plasma creation and condensation
Every chemical has a decomposition temperature. My understanding is that above that temperature molecular bonds are broken. And if we raise the heat high enough then all molecular bonds will break ...
- 3,340
4
votes
1
answer
998
views
How to estimate the dielectric constant of a liquid?
Are there any approximate relationships between the (static) dielectric constant of a liquid and properties of the individual molecules?
For example, suppose I know the polarizability and dipole ...
- 917
2
votes
1
answer
82
views
Polymers with no molecular mass distribution?
What sort of ideal conditions are required - theoretically - to conduct polymerization reactions to make all the macromolecules end up with exactly the same molecular mass, just like the products in ...
- 517
6
votes
2
answers
814
views
Measuring Thermodynamic Stability
We can predict whether a reaction can occur spontaneously by calculating the change in Gibbs' free energy.
I was just wondering whether there is any general measure of the thermodynamic stability of ...
- 2,135