Question

1 mole of $N{H}_3$ gas at ${27}^{0}C$ is expanded adiabatic condition to make volume 8 times $(\gamma =1.33)$. Final temperature and work done respectively are:

• A. $150K,900cal$
• B. $150K,400cal$
• C. $250K,1000cal$
• D. $200K,800cal$

Answer 1

The correct option is A $150K,900cal$

Work done in adiabatic process $=n\frac{R}{\gamma -1}\Delta T$

$W.D.=1\times \frac{2}{.33}\times 150=900cal$

And for temperature

$T_1{V}_1^{\gamma -1}=T_2{V}_2^{\gamma -1}$

$\frac{300}{T_2}=[\frac{V\times 8}{V}{]}^{1.33-1}$

So $T_2=150K$