Question

A gas mixture consists of 2.0 moles of oxygen and 4.0 moles of neon at temperature T. Neglecting all vibrational modes, calculate the total internal energy of the system. (Oxygen has two rotational modes.)

Answer 1

Oxygen has 5 degree of freedom `:.` Energy per mole of oxygen = `5/2 RT`
For 2 moles of oxygen , energy, `E_(1) = 5RT`
Neon has 3 degrees of freedon `:.` Energy per mole of neon = `3/2 RT`
For 4 moles of neon energy , `E_(2) = 4 xx 3/2 RT = 6RT`
Total energy of mixture = `E_(1)+E_(2)= 5RT + 6RT= 11 RT`.