The molar specific heat at constant pressure of an ideal gas is (7/2) $R$. The ratio of specific heat at…
The molar specific heat at constant pressure of an ideal gas is (7/2) $R$. The ratio of specific heat at constant pressure to that at constant volume is:
$9 / 7$
$7 / 5$
$8 / 7$
$5 / 7$
Solution
Molar specific heat at constant pressure
$C_P=\frac{7}{2} R$
We know that $C_P-C_V=R$
$\Rightarrow \quad \begin{aligned}
C_V & =C_P-R \\
& =\frac{7}{2} R-R=\frac{5}{2} R
\end{aligned}$
from (i) and (ii),
$\therefore \quad \frac{C_P}{C_V}=\frac{7}{5} .$
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