Question

When $2$ moles of $O_{2}$ and $1$ mole of $He$ are mixed together, then the ratio of $C_{p}/C_{v}$ for the mixture is

• A. $\frac{19}{13}$
• B. $\frac{13}{19}$
• C. $\frac{13}{6}$
• D. $\frac{6}{13}$

Answer 1

Answer: (A)

$C_{v}=\frac{2 \times \frac{5}{2} R + 1 \times \frac{3}{2} R}{3}$
$=\frac{1}{3}\left[5 R + \frac{3 R}{2}\right]$
$=\left(\frac{13}{2} R\right)\frac{1}{3}=\frac{13}{6}R$
$C_{p}=\frac{19}{6}R$
$\frac{C_{p}}{C_{v}}=\frac{19}{13}$