Phase Diagrams and Vapor Pressure Diagrams

A phase diagram is a graph of pressure versus temperature that shows the specific condition ranges under which the substance exists in its three phases, solid, liquid and gas. It is possible for a substance to change phase without changing temperature. This key concept is revealed through the analysis of a phase diagram. Can you imagine boiling a substance without actually heating the substance? This idea is quite profound and usually met with great skepticism. You must remember that pressure also has an effect on phase changes. In this topic, you will analyze phase diagrams to learn how pressure affects phase changes. You will also learn the difference between a gas and a vapor.

Essential Question

• How are both phase diagrams and vapor pressure diagrams analyzed?