Advanced Placement (AP) Chemistry Practice Exam

What occurs to the molecules of a gas as represented by Maxwell-Boltzmann diagrams?

1. They maintain a constant velocity

2. They exhibit a range of velocities

3. They experience a sudden increase in mass

4. They form bonds to create larger molecules

The correct answer is: They exhibit a range of velocities

The correct answer highlights the key concept that gas molecules exhibit a range of velocities, which is a fundamental aspect of the kinetic molecular theory of gases. Maxwell-Boltzmann diagrams illustrate the distribution of speeds of gas molecules at a given temperature. In these diagrams, the x-axis represents the speed of the molecules, while the y-axis indicates the number of molecules that possess those speeds. At any given temperature, gas molecules do not all move at the same speed; instead, they have a distribution of speeds due to collisions and variations in energy. The shape of the Maxwell-Boltzmann distribution curve demonstrates that while some molecules may be moving relatively slowly, others can be moving much faster, resulting in a bell-shaped curve that indicates this range of velocities. The other options do not accurately reflect the behavior of gas molecules as illustrated by the Maxwell-Boltzmann distribution. Gas molecules do not maintain a constant velocity, nor do they experience a sudden increase in mass or form bonds to create larger molecules under normal conditions in a gaseous state. Thus, the explanation provided by the correct choice encapsulates the essential idea that gas molecules possess a variety of speeds, contributing to the overall behavior and properties of gases.