Which of the following statements is/are true about the kinetic molecular theory of gases?
Which of the following statements is/are true?
I) At a given temperature, larger molecules
have a greater average kinetic energy
than smaller molecules.
II) As the temperature of a gaseous system
rises, the average speed of gas molecules
increases.
III) Gas molecules have an average rate of
diffusion that is lower than their average
speed in a vacuum
Which of the following statements is/are true?
I) At a given temperature, larger molecules
have a greater average kinetic energy
than smaller molecules.
II) As the temperature of a gaseous system
rises, the average speed of gas molecules
increases.
III) Gas molecules have an average rate of
diffusion that is lower than their average
speed in a vacuum
1 Answer
Only II is true.
Explanation:
(I is false.)
At a given temperature, the average kinetic energy is proportional to that temperature. This means that large molecules have the same average kinetic energy as small molecules under the equipartition theorem.
Think of a mach truck it is traveling slower than a sports car but because of its greater mass it has the same kinetic energy. The smaller sports car has much less mass, but at 100 miles per hour has the same kinetic energy as the mach truck.
(II is true.)
Temperature is actually a measure of average kinetic energy.
As the temperature increases the kinetic energy increases.
(III is false.)
In a vacuum there are fewer gas particles, so the mean-free path is longer. Thus, the speed of the molecules in a vacuum is higher.
