Question

When 229 j of energy is supplied as heat to 3.0 mol ar (g), the temperature of the sample increases by 2.55 k. calculate the molar heat capacities at constant volume and constant pressure of the gas?

Answer 1

At constant pressure,
      Cp=Δq/nΔT 
       
      Cp=229/3*2.55=29.93 Jmol-1K-1
and, 

Cp-Cv=R  (Mayer's formula)

so, 

Cv=Cp-R

Cv=29.93-8.314

Cv==21.616 Jmol-1K-1
 

Answer 2

Cp-Cv=nR

Cp=q/∆T=229/2.55=89.80 J/K

Cv=Cp-nR=89.80-3*8.314=64.86J/K

Cv/mol=64.86/3=21.6J/K