Question

A gas mixture consists of 2moles of oxygen and 4moles of Ar at temperature T. Neglecting all vibrational modes, the total internal energy of the system is

• A. 4 RT
• B. 15 RT
• C. 9 RT
• D. 11 RT

Answer 1

The correct option is D 11 RT

The internal energy of the system is given as $U=n(\frac{f}{2}R)T$. Here f is the degree of freedom which is 5 for oxygen(diatomic molecule) and 3 for argon(monoatomic molecule). Thus we get the total internal energy as $2(\frac{5}{2})RT+4(\frac{3}{2})RT=11RT$