New answers tagged thermodynamics
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How to derive the relation between gibbs energy and equilibrium constant?
The Boltzmann equation is actually derived from an entropy and energy argument. I think Banjaminson does a decent job, but I'll provide a brief overview as it's relevant.
Assume that we have some ...
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What is the difference between standard Gibbs energy and Gibbs energy of formation?
Here are the two definitions again:
$$\Delta G_{Rx} = \Delta G_f^{products} - \Delta G_f^{reactants}\tag{1}$$
$$ \Delta G^o_{Rx} = \sum_i s_i \Delta G_{f,i}^o \tag{2}$$
What exactly is the difference ...
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How to convert molar volume to volume?
If you have given
the molar volume $V_\text{m}$ in $\pu{cm3 mol-1}$,
the molar amount in $\pu{mol}$,
you get the volume as $V = n \cdot V_\text{m}\ [\pu{cm3}] = 0.1 \cdot n \cdot V_\text{m}\ [\pu{J ...
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What's the minimum amount of energy needed to remove CO2 from the atmosphere?
There are free, natural, methos of removal of CO2 from the air, rainfall that dissolves CO2 that eventually resides in the Ocean as bicarbonate, and biological sequestration by plants etc. that give ...
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How can enthalpy of an ideal gas be independent of pressure?
The statement means that enthalpy is independent of pressure, for an ideal gas, if temperature and the amount of matter are both held constant.
For example, if you have 1 mol of idealium on Earth's ...
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Change in internal energy at constant pressure versus heat released at constant volume
You are first trying to find the internal energy change for the reaction at constant temperature and pressure, given the enthalpy change at the same temperature and pressure. So we are using $$\Delta ...
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Possible error in textbook question? (Heat transfer)
The log-mean temperature difference arises from your original equation: $$(\frac{T_{out} - T_w}{T_{in} - T_w})=exp(\frac{-\pi{d}L}{m{C_p}{R_H}})$$or$$\ln{\left(\frac{T_{out} - T_w}{T_{in} - T_w}\...
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Possible error in textbook question? (Heat transfer)
I figured out the problem with my working. I used the following equation earlier:
$(\frac{T_{out} - T_w}{T_{in} - T_w})=exp(\frac{-\pi{d}L}{m{C_p}{R_H}})$
This was the wrong equation to use because it ...
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Possible error in textbook question? (Heat transfer)
Overall resistance $R= 0.4545+0.14+\frac{0.002}{.4}=0.5995\ (m^2C)/kW$
Heat Transfer coefficient $U=\frac{1}{R}=1.6681\ kW/(m^2C)$
log mean temperature difference $=\frac{85-40}{\ln{(85/40)}}=59.7\ C$
...
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What solvents can I use to dissolve Epichlorohydrin rubber and Chloroprene Rubber
For chloroprene (neoprene), you might try chlorinated solvents, e.g., methyl chloride (chloromethane).
Epichlorohydrin has "Inferior resistance to oxygenated solvents," according to River ...
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How can I model the melting of ice as a function of time?
As a very, very crude, 'ball-park' or 'back of envelope' etc. estimate we can use the thermal diffusion coefficients of ice and water. The values for ice and water are $\approx 1$ and $0.14$ mm$^2$/s ...
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Understanding Rossini and Frandsen experiment for measuring $(\partial u/\partial P)_T$?
One form of the general virial equation of state for a real gas is $$\frac{Pv}{RT}=1+B^*(T)P+C^*(T)P^2+...$$where v is the molar volume. At low pressures, this approaches $$\frac{Pv}{RT}=1+B^*(T)P$$
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How can standard enthalpies of fusion and vaporization add up to that of sublimation when these occur at different temperatures?
You can certainly have liquid and vapor at equilibrium at temperatures other than the atmospheric boiling point. And you can certainly have solid and vapor at equilibrium at temperatures less than ...
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Doubt regarding isothermal reversible process- Thermodynamics
Welcome to Chemistry SE Ainesh.
This is a common doubt that students all over the world have. In order to dispel it, it pays to have a glimpse of exactly what process each equation is describing. The ...
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Doubt regarding isothermal reversible process- Thermodynamics
For a reversible process, you are right in saying that $P_\text{int}= P_\text{ext}$; however, this pressure is not constant. As the gas compresses or expands, the pressure changes, and as a result it ...
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Doubt regarding isothermal reversible process- Thermodynamics
For a massless-frictionless piston, applying Newton's 2nd law gives $$F_g=P_{ext}A$$where $F_g$ is the force that the gas exerts on the piston. So the work the gas does on the piston is $$W=\int{...
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Non-Constant Pressure and Temperature Processes - Gibbs Energy as Equilibrium Condition
This answer was deleted with no explanation. I am resubmitting trusting the moderator will explain the problem.
As you finally seem to conclude when equilibrium is attained T, P, and activities of all ...
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Why is more work done for a reversible process?
You're right to be confused. The diagram you show is neither a proof nor an intuitive explanation. It can't be a proof because the statement "reversible processes do more work than irreversible ...
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Dewpoint of water in relation to composition of atmosphere
Gases do not hold water vapor. Vapor is gas on its own. Neither oxygen nor nitrogen need other gases to hold them either. Gases are mutually toward each other just bystanders. Vapor can be present in ...
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