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### Final Temperature at Constant Pressure, and then at Constant Volume

Posted: Fri Feb 01, 2019 3:52 pm
Hey guys,
I am working on problem 4C.3, which asks to calculate the final temperature and the change in enthalpy when 765 J of energy is transferred as heat to 0.820 mol Kr (g) at 298 L and 1.00 atm.
I know how to calculate the final temperature and enthalpy with this information but I am unsure of how to calculate that with constant pressure and then with constant volume. If someone could explain to get me started it would be much appreciated!

### Re: Final Temperature at Constant Pressure, and then at Constant Volume

Posted: Sat Feb 02, 2019 11:09 am
Hi Mariah!

I'm assuming that you mean T = 298 K and not V = 298 L. As such, the volume won't be constant, but the pressure will be. So I don't think you need to worry about there being a constant volume since we don't know if the gas does any work. We know that no work is done ON the gas, but by adding heat, we could make the gas DO work.

Hope that helps!

### Re: Final Temperature at Constant Pressure, and then at Constant Volume

Posted: Mon Feb 04, 2019 2:09 pm
For this question you need to know that for an ideal gas Cp(specific heat at constant pressure) = (5/2) R and at constant volume is Cv = (3/2) R where R is equal to 8.312 J*K-1*mol-1.

You can find these values on the constant and formulas sheet.
Hope this helps!