Q.

500 J of energy is transferred as heat to 0.5 mol of Argon gas at 298 K and 1.00 atm. The final temperature and the change in internal energy respectively are:        [2025]

1 378 K and 300 J  
2 348 K and 300 J  
3 368 K and 500 J  
4 378 K and 500 J  

Ans.

(2)

As heat is transferred at constant pressure, all the heat transferred changes enthalpy of the system.

qp=ΔH

500=nCpΔT

500=0.5×52R×(Tf-298)

500=0.5×52×8.3×(Tf-298)

Tf=346.19K

ΔUΔH=nCvΔTnCpΔT =n(32)RΔTn(52)RΔT =35

ΔU500=35

ΔU=300 J