All Questions
Tagged with pressure thermodynamics
8 questions
6
votes
1
answer
54k
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Reversible and Irreversible adiabatic expansion
A $\mathrm{200.0\ m^3}$ balloon at $253.0\ \mathrm K$ ascends to a higher altitude. If the initial pressure inside the balloon is $325$ millibar, and it ascends to a latitude with a pressure of $7.45$ ...
- 161
12
votes
4
answers
14k
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Why do we use the external pressure to calculate the work done by gas
I read in a textbook that in the case when we have a gas in a cylinder fitted with a massless frictionless piston being held with an external pressure $p_1$, and when the pressure is reduced to become ...
user38257
6
votes
1
answer
22k
views
Entropy and specific heat capacity
I have seen the equation $S(T_2)=S(T_1)+C_p\ln(T_2/T_1)$ where $C_p$ is the molar heat capacity at a constant pressure. I understand that this assumes that the temperature range is sufficiently small ...
- 1,717
4
votes
2
answers
2k
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Does enthalpy equal heat when PV work is done?
The derivation that enthalpy equals heat at constant pressure goes like:
$$\begin{align}
H &= U + P_{\mathrm{int}}V \\
\Delta H &= \Delta U + \Delta (P_{\mathrm{int}}V)
\end{align}$$
If $P_{\...
- 2,052
3
votes
4
answers
2k
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Enthalpy of a reaction changes with temperature, does this mean bond strengths change with temperature?
During chemical reactions, the bonds between atoms break or form to either absorb or release energy. The result is a change to the potential energy of the system. The heat absorbed or released from a ...
3
votes
2
answers
5k
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Van der Waals real gas equation
Van der Waals corrected the ideal gas equation for real gases and gave the following equation:
$$\left(p+\frac{an²}{V^2}\right)\left(V-nb\right)=nRT$$
I’m very confused about one aspect of this ...
user33789
1
vote
2
answers
604
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Which pressure is used for calculation of standard enthalpy change of the reaction with two or more gases?
Standard state conditions for standard Gibbs free energy change stipulate (among other conditions) that the partial pressure of each gas is $\pu{1 bar},$ e.g. for the reaction
$$\ce{2 A(g) + 3 B(g) &...
1
vote
1
answer
182
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When fugacity and z-compressability equations instead of Gibbs free energy equations?
In very high pressure environments such as mud circulating systems, conditions for polymers contain fugacity/z-compressability criteria instead of Gibbs free energy, more in the answer. So
When ...
- 256