Question

The average translational energy and the rms speed of molecules in a sample of oxygen at 300K are 6.21 x 10^-21J and 484 m/s respectively. The corresponding values at 600K are nearly (assuming ideal gas behavior).

• A. 12.42 x 10^-21J, 968 m/s.
• B. 6.21 x 10^-21J, 968 m/s
• C. 8.78 x 10^-21J, 684m/s
• D. 12.42 x 10^-21J, 684 m/s

Answer 1

Answer: (D)

12.42 x 10^-21J, 684 m/s

Answer 2

$\mathrm { KE } = \frac { 3 } { 2 } \mathrm { KT }$,

i.e.

$\therefore$ $\mathrm { KE } _ { 2 } = 2 \mathrm { KE } _ { 1 } = 2 \times 6.21 \times 10 ^ { - 21 }$ = 12.42 × 10^-21J

$\frac { \mathrm { V } _ { \mathrm { rms } , 2 } } { \mathrm {~V} _ { \mathrm { rms } , 1 } } = \sqrt { \frac { \mathrm { T } _ { 2 } } { \mathrm {~T} _ { 1 } } }$ = √2

$\therefore$
= 684 m/s.

Hence (4) is correct