Question

If a gas mixture contains 2 moles of $O_2$ and 4 moles of Ar at temperature $T$, then what will be the total energy of the system (neglecting all vibrational modes)

• A. 11 RT
• B. 15 RT
• C. 8 RT
• D. RT

Answer 1

The correct option is A 11 RT

Given, At a temperature $T$,

Number of moles of $O_2=2moles$

Number of moles of $Ar=4moles$

We Know,

Total energy of the gases,
$U=2\left(\begin{array}{c}\frac{n_1}{2}RT\end{array}\right)+4\left(\begin{array}{c}\frac{n_2}{2}RT\end{array}\right)$
For $O_2,n_1=5$ and for $Ar,n_2=3$
$\therefore U=2\left(\begin{array}{c}\frac{5}{2}RT\end{array}\right)+4\left(\begin{array}{c}\frac{3}{2}RT\end{array}\right)=11RT$