Question

What is the sum of translational and rotational energy of 1 mole of oxygen at $300\text{K}$ ?
$R=8.314{\text{J mol}}^{-1}{\text{K}}^{-1}$

• A. $6235.5\text{J}$
• B. $623.25\text{J}$
• C. $62.325\text{J}$
• D. $6.2325\text{J}$

Answer 1

The correct option is A $6235.5\text{J}$

For $O_2$ (diatomic) molecule:
Translational degree of freedom = 3,
and rotational degree of freedom = 2, so
$\text{Translational energy},E_T=\frac{3}{2}RT,\text{Rotational energy},E_R=RT$

Here, Temperature $T=300K$, $R=8.314{\text{J mol}}^{-1}{\text{K}}^{-1}$

$E_{\text{total}}=\frac{3}{2}RT+RT=\frac{5}{2}RT=\frac{5}{2}\times 8.314\times 300=6235.5\text{J}$