8.31

[Mike Matthews 1D]

Could someone please explain to me how to do homework problem 8.31, "Calculate the heat released by 5.025 g of Kr(g) at 0.400 atm as it cools from 97.6 degrees Celsius to 25.0 degrees Celsius at a. a constant pressure and b. constant volume. Assume that krypton behaves like an ideal gas." Which equation would I use to solve this problem and why?
Thanks.

[Laura Riccardelli]

I believe that you should use the equation q=(M)(change in T )(specific heat capacity)
the solution maple also has you using the equations Cp,m=(5/2) R to find the specific heat capacity for the ideal gas at an constant pressure and Cv,m= (3/2) R for the molecule at a specific volume. I am confused on if we need to know these equations to find specific heat or not.

[PeterTran1C]

It is also good to note that part (a) contains a monatomic ideal gas at a constant pressure while part (b) contains a monataomic ideal gas at constant volume.

[Yixin Angela Wang 2H]

Which gas constant R do we use, and how do we choose?

[Leah Savage 2F]

I believe you use R=8.314 J/(K)(mol). I don't think it really matters which you use; but you must pick the one that cancels with the units you already have in the problem to leave you with joules.