Question

A diatomic .gas $(\gamma =1.4)$ does $2000J$ of work when it is expanded isobarically. Find the heat (in $kJ$ ) given to the gas in the above process.

Answer 1

Answer: 7

For a diatomic gas, $C_v=\frac{5}{2}R$
and $C_p=\frac{7}{2}R$.
The work done in an isobaric process is
$W=P\left(V_2-V_1\right)=nR{T}_2-nR{T}_1$
$\Rightarrow T_2-T_1=\frac{W}{nR}$
The heat given in an isobaric process is .
$Q=n{C}_p\left(T_2-T_1\right)=n{C}_p\frac{W}{nR}=\frac{7}{2}\times W$
$=\frac{7}{2}\times 2000J=7000J$