### Textbook Question

Posted: **Thu Feb 07, 2019 10:00 am**

by **Riya Shah 4H**

Calculate the heat released by 5.025 g of Kr(g) at 0.400 atm as it cools from 97.6 C to 25.0 C at

(a) constant pressure and

(b) constant volume. Assume that krypton behaves as an ideal gas.

Could someone please explain this?

### Re: Textbook Question

Posted: **Thu Feb 07, 2019 12:40 pm**

by **Nada AbouHaiba 1I**

So for this problem you're gonna wanna use the ideal gas equations, Cp (constant pressure) is 5/2 of the gas constant (which is 8.314) and Cv (constant volume) 3/2 of the same gas constant. One you calculate the C for each scenario you'll plug it into equation nCdeltaT to solve for q which is the heat released.

For example,

Cp = 5/3(8.314) = 20.875

5.025 g Kr/83.798 g/mol = .05997 moles Kr

q=(.05997)(20.785)(25.0-97.6) = -90.5 J

Then you'll just do the same thing for Cv all that changes is the heat capacity

Hope this helps:)