AP® Chemistry

Free Version

Upgrade subject to access all content


Unusual Gas Behavior


A gaseous compound is heated at constant pressure. The figure below shows the variation of volume as the temperature is increased.

Created for Albert.io. Copyright 2016. All rights reserved.

At first, the volume increases in a steady fashion as predicted by Charles' law. Then, all of a sudden, at Point A, the volume starts to increase at a more rapid rate.

Which of the following is a possible explanation for this behavior?


Gases cease to behave ideally at elevated temperatures.


The molecules of gas have begun to dissociate.


Point A is the critical point for this substance.


A change of state is occurring.