I am struggling with this AP Chemistry Problem

Question

A balloon filled with 39.9 mol of helium was a volums of 876 L at 0.0°C and 1 atm. The temperature of the balloon increased from 38.0°C as it expands to a volume of 998L, the pressure remaining constant. Calculate q,w, and change in E. The molar heat capacity of He is 20.i J/°C•mol.

Answer 1

q = mcdelT = (39.9 mol)(20.1 J/C n) (38.0) = 3.05 x 10^4 J = 30.5 kJ

 

w = P del V = 1 atm (122 L) = 122 atm L = 122 kJ

 

Del E = q + w = 30.5 kJ + 122 kJ = 152.5 = 153 kJ