If an ideal gas molecule has a speed of 0.50 km/s at 20°C,what is its speed at 80°C?
A)500 m/s
B)550 m/s
C)1000 m/s
D)2000 m/s

Question

Quizplus · Accepted Answer

According to the kinetic theory of gases, the average kinetic energy of gas molecules is directly proportional to the temperature. Therefore, if the temperature increases by a factor of 4 (from 20°C to 80°C), the average kinetic energy of gas molecules will also increase by a factor of 4. Since the kinetic energy of a gas molecule is proportional to the square of its speed, we can say that the speed of the gas molecule will increase by a factor of 2. Therefore, the speed at 80°C will be 0.50 km/s x 2 = 1 km/s = 1000 m/s. The closest answer choice to this is B (550 m/s), which is approximately half of the actual speed.

If an Ideal Gas Molecule Has a Speed of 0