Chapter 12.6, Problem 7PPC

(a)

Interpretation Introduction

Interpretation:

Three phase diagrams are given as follows –

Figure 1

The correct phase diagram which has the arrows representing the following changes has to be identified.  Apart from the phase diagram in the correct option, for the other two phase diagrams a numbered list of changes has to be written.

1. 1. Temperature increase with no phase change

1. 2. Pressure decrease causing a solid-to-vapor phase change

1. 3. Temperature increase with no phase change.

1. 4. Pressure increase with vapor-to-liquid phase change and liquid-to-solid phase change

1. 5. Temperature increase with solid-to-liquid phase change.

1. 6. Pressure decrease with liquid-to-vapor phase change

Concept Introduction:

• Phase change refers to change in physical state of a substance.  If a substance undergoes change in its physical state from one physical form to another physical form, then the substance is said to be undergone phase change.
• Phase diagram illustrates temperature and pressure conditions at which a substance can remain stable at a certain physical state. The distinct separation between the different phases of a system is known as phase boundary.

(b)

Interpretation Introduction

Interpretation:

For phase diagram (ii), the arrows in it represent the following changes –

• Increase in temperature, no phase change.
• Increase in pressure, phase change from vapor to solid.
• Increase in temperature, phase change from solid to liquid to vapor.
• Increase in pressure, phase change from vapor to liquid
• Decrease in temperature, phase change from liquid to solid.
• Increase in pressure, no phase change.

For phase diagram (iii) the arrows in it represent the following changes –

• Increase in temperature, phase changes from solid to vapor.
• Decrease in pressure, no phase change.
• Increase in temperature, no phase change.
• Increase in pressure, phase change from vapor to liquid to solid.
• Increase in temperature, no phase change.
• Decrease in pressure, phase change from solid to liquid to vapor.

      Concept Introduction:

• Phase change refers to change in physical state of a substance.  If a substance undergoes change in its physical state from one physical form to another physical form, then the substance is said to be undergone phase change.
• Phase diagram illustrates temperature and pressure conditions at which a substance can remain stable at a certain physical state. The distinct separation between the different phases of a system is known as phase boundary.