Question

The average energy of molecules in a sample of oxgen gas at $300 \, K$ are $6.21 \times 10^{-21 \, J}$. The corresponding values at $600\, K$ are

• A. $6.21 \times 10^{-21} \, J$
• B. $8.78 \times 10^{-21} \, J$
• C. $4.21 \times 10^{-21} \, J$
• D. $12.42 \times 10^{-21} \, J$

Answer 1

Answer: (D)

The average kinetic energy of molecules in a sample of oxygen gas is given by
$KE_{avg} = \frac{3}{2}kT\, or \, \frac{(KE_{avg})_{1}}{(KE_{avg})_{2}} = \frac{T_{1}}{T_{2}}$
$(KE_{avg})_{1} =6.21 \times10^{-21} J, T_{1} =300 K$
$T_2 = 600 \, K , (KE_{avg})_2 = ?$
$\therefore \:\:\: \frac{6.21 \times10^{-21}}{(KE_{avg})_{2}} =\frac{300}{600} =\frac{1}{2}$
$ (KE_{avg})_{2} = 12.42 \times10^{-21} J$