Question

2 mole $He$ is mixed with 2 g of $H_2$. The molar heat capacity at constant pressure for the mixture is:

• A. $\frac{17R}{6}$
• B. $\frac{11R}{6}$
• C. $4R$
• D. $\frac{3R}{2}$

Answer 1

The correct option is A $\frac{17R}{6}$

$C_{P_1}\text{for}{}^{\prime }H{e}^{\prime }\text{(monoatomic)}=\frac{5}{2}R$
$C_{P_2}$ for $H_2\left(diatomic\right)=\frac{7}{2}R$
Given,
Moles of $He$ $\left(n_{He}\right)=2$
Moles of $H_2\left(n_{H_2}\right)=1$
$\therefore C_P=\frac{n_1{C}_{P_1}+n_2{C}_{P_2}}{n_1+n_2}$
$=\frac{2\times \frac{5}{2}R+1\times \frac{7}{2}R}{3}$
$=\frac{17R}{6}$