Question

The temperature of $5moles$ of a gas which was held at constant volume was changed from ${100}^{o}C$ to ${120}^{o}C$. The change in the internal energy of the gas was found to be $80J$. The total heat capacity of the gas at constant volume will be equal to

• A. $0.4J{K}^{-1}$
• B. $4J{k}^{-1}$
• C. $0.8J{K}^{-1}$
• D. $8J{K}^{-1}$

Answer 1

Answer: (B)

$4J{k}^{-1}$

At constant volume work done = 0, and hence total heat supplied = change in internal energy

change in internal energy = $n{C}_{v}dT$

$80J=5C_v\left(20\right)$

$C_v=0.8\frac{J}{k}$

Total heat capacity = $5\left(0.8\right)=4\frac{J}{k}$