Question

Question: 0.37 litre of an ideal monatomic gas (Cv,m = 3R/2) initially at 51 °C and 36 atm pressure undergo an expansion against a constant external pressure of 1.06 atm, and do 2.3 kJ of work. The final pressure of the gas is 1.06 atm. Calculate the change in enthalpy, ΔH.

First, I calculated Vf using the equation W = -Pext(Vf-Vi) and found Vf to be 2170.18L.

Then, I used P1V1 = nRT1 to find n, which found to be 0.50075 moles.

Next, I used Tf = (PfVf)/(nR), and Tf = 55981.3 K.

Finally, I used ΔH = n(5R/2)(Tf - Ti) and found ΔH = 57929.19.
The answer I got is wrong :( can you please point out where I did wrong? Thank you so much