Question

The ratio $\frac{C_p}{C_c}=\gamma$ for gas. Its molecular weight is 'M'. Its specific heat capacity at constant pressure is :

• A. $\frac{R}{\gamma -1}$
• B. $\frac{\gamma R}{\gamma -1}$
• C. $\frac{\gamma R}{M(\gamma -1)}$
• D. $\frac{\gamma RM}{(\gamma -1)}$

Answer 1

The correct option is C $\frac{\gamma R}{M(\gamma -1)}$

Since $C_P-C_V=\frac{R}{M}$ and $\frac{C_P}{C_V}=\gamma$,

$C_V=\frac{R}{M(\gamma -1)}$

and $C_P=\frac{\gamma R}{M(\gamma -1)}$

Now, at constant pressure, $Q=\Delta H=n{C}_P\Delta T=\frac{\gamma R}{M(\gamma -1)}$