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)

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