When 229 J of energy is supplied as heat to 3.0 mol of Ar (g) ,

the temperature of the sample increases by 2.55K .

Calculate the molar heat capacities at constant volume and constant pressure of the gas.

(Exercise :Atkins physical chemistry 8th p.p71 2.12 (a)

Answer : Cp,m = 30 J /K mol and Cv,m =22 J /K mol)

To start this question,

I first think of the change in temperature is positive, so it is not adiabatic change.

W=229

Ar=3.0 mol

temp : + 2.55K

So i use the formula

q_{p}= Cp (Tf-Ti )

229 = Cp (2.55K)

Cp = 89.8 J / mol

therefore Cp,m = 89.8 J mol^{-1} /3mol = 30 J / K mol

which is the correct answer.

But i cant come out with Cv,m

i try to use Cv,m = Cv/ n = Cv/3.0

and i cant continue from here

i wonder is there any relation between Cv and Cp??