Which of the following is not a postulate of the kinetic molecular theory?
A. The collisions between gas molecules are elastic.
B. The energy of a gas molecule is determined by quantum mechanics.
C. Gas molecules travel in random, straight paths.
D. The absolute temperature of a substance is equal to the average kinetic energy of its particles.
B. The energy of a gas molecule is determined by quantum mechanics.
The correct answer is B. The energy of a gas molecule is determined by quantum mechanics. This is not a postulate of the kinetic molecular theory. The kinetic molecular theory only focuses on the macroscopic properties of gases and does not consider quantum mechanical effects on gas molecules.
To determine which of the options is not a postulate of the kinetic molecular theory, we first need to understand what the kinetic molecular theory says.
The kinetic molecular theory is a model used to explain the behavior of gases based on the motion of individual gas molecules. It makes several fundamental assumptions, or postulates, about the behavior of gas particles.
Let's analyze each option to see if it aligns with the postulates of the kinetic molecular theory:
A. The collisions between gas molecules are elastic.
This statement is consistent with the kinetic molecular theory. According to the theory, gas molecules do indeed collide with each other and these collisions are elastic, meaning that no energy is lost during the collision.
B. The energy of a gas molecule is determined by quantum mechanics.
This option suggests that the energy of a gas molecule is determined by quantum mechanics. While quantum mechanics plays a crucial role in understanding the behavior of atoms and molecules, it is not explicitly included as a postulate of the kinetic molecular theory. Therefore, option B is a plausible candidate for the answer.
C. Gas molecules travel in random, straight paths.
This statement aligns with the kinetic molecular theory. According to the theory, gas molecules move in constant, random motion, with each molecule traveling in a straight line until it collides with another molecule.
D. The absolute temperature of a substance is equal to the average kinetic energy of its particles.
This statement is also consistent with the kinetic molecular theory. According to the theory, the absolute temperature of a substance is directly proportional to the average kinetic energy of its particles. Therefore, option D is in line with the postulates of the theory.
After analyzing each option, we can conclude that option B, "The energy of a gas molecule is determined by quantum mechanics," is not a postulate of the kinetic molecular theory.