Calculate the heat capacity at constant volume and constant pressure.

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SUMMARY

The discussion revolves around calculating the molar heat capacities at constant volume (CV) and constant pressure (CP) for a gas given specific parameters: 178 J of heat supplied, 1.9 moles of gas, and a temperature change of 2.55 K. The key equations involved are q = C*T, CP - CV = nR, and U = q + w. The main issue highlighted is the ambiguity in the problem regarding whether the temperature change occurs at constant volume or constant pressure, which complicates the calculation.

PREREQUISITES
  • Understanding of thermodynamic principles, specifically heat capacity.
  • Familiarity with the ideal gas law and its applications.
  • Knowledge of the first law of thermodynamics.
  • Basic algebra for manipulating equations.
NEXT STEPS
  • Study the derivation and application of the heat capacity formulas CV and CP.
  • Learn about the ideal gas law and its implications for heat transfer.
  • Explore the first law of thermodynamics and its relevance to heat and work.
  • Review common problems involving heat capacity calculations in thermodynamics.
USEFUL FOR

Students studying thermodynamics, particularly those preparing for exams involving heat capacity calculations, and educators seeking clarity on teaching these concepts effectively.

LogicX
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Homework Statement



I am given the amount of moles of gas, how many joules of heat I put into the system, and a positive change in temperature. Then it says "calculate the molar heat capacities at constant volume and constant pressure of the gas."

Homework Equations



q=CT, C(constant pressure)-C(constant volume)=nR, U= q+w, H=U+PV

The Attempt at a Solution



I just don't know how to do this problem without knowing whether the temperature change occurs at constant volume or constant pressure. If I knew either of those the problem would be easy.

I have q and delta(T), so I should be able to calculate a heat capacity. But I don't know which one it would be.
 
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Can you give exact wording of the question? Perhaps the information is there, just hidden?
 
"When 178 J of energy is supplied as heat to 1.9 mol of gas molecules, the temperature of the sample increases by 2.55 K. Calculate the molar heat capacities at constant volume and constant pressure of the gas."
 
Nah, you are right - question is unclear.
 
Borek said:
Nah, you are right - question is unclear.

Ok thanks, I'll go talk to my professor tomorrow.
 
Well my professor is a senile old man so I tried to ask him today, but he seemed to have a mental block against admitting he wrote the question wrong so at first he tried to tell me I can assume the pressure is constant, then that I can assume that the volume is constant.

I guess I just have to hope that he doesn't pull this **** on the exam because he would probably just arbitrarily pick one that he wanted us to assume was constant and if I confronted him about it get the same talking in circles answer that I got just now.

I hate college sometimes.
 

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