Question

At what temperature will the total K.E. of 0.3 mol of He be the same as the total K.E. of 0.4 mol of Ar at 400 K

• A. 400 K
• B. 300 K
• C. 346 K
• D. 533 K

Answer 1

Answer: (D)

533 K

Answer 2

K.E. of n moles of a gas, K.E. = $\frac{3}{2}$nRT K.E, = $\frac{3}{2} n_1 \,RT_1$ $K.E_2 = \frac{3}{2} n_2 \, RT_2$ $K.E_1 = K.E_2$ $n_1T_1 = n_2T_2$ 0.3 $\times$ T , = 0.4 $\times$ 400 $T_1 = \frac{1600}{3}$ = 533 K