Chapter 12, Problem 12.111QP

(a)

Interpretation Introduction

Interpretation:

In the given phase diagram, the maximum temperature for the existence of helium-II, has to be found.

Concept Introduction:

Phase diagram: In any phase diagram, the thick lines indicate the equilibrium existing between two phases. In the given phase diagrams, the very 1^st phase from the top is the solid phase and the next adjacent phase is the liquid phase. The phase below the liquid phase is the gaseous phase which will be the bottom portion of the entire phase diagram.

(b)

Interpretation Introduction

Interpretation:

In the given phase diagram, the minimum pressure for the existence of solid helium, has to be found.

Concept Introduction:

Phase diagram: In any phase diagram, the thick lines indicate the equilibrium existing between two phases. In the given phase diagrams, the very 1^st phase from the top is the solid phase and the next adjacent phase is the liquid phase. The phase below the liquid phase is the gaseous phase which will be the bottom portion of the entire phase diagram.

(c)

Interpretation Introduction

Interpretation:

In the given phase diagram, the normal boiling point of helium-I has to be found.

Concept Introduction:

Phase diagram: In any phase diagram, the thick lines indicate the equilibrium existing between two phases. In the given phase diagrams, the very 1^st phase from the top is the solid phase and the next adjacent phase is the liquid phase. The phase below the liquid phase is the gaseous phase which will be the bottom portion of the entire phase diagram.

Defining boiling point:

Boiling point is the temperature at which the vapor pressure of a substance will be in equilibrium with the external pressure.

(d)

Interpretation Introduction

Interpretation:

From the given phase diagram, whether solid helium can sublime or not has to be found.

Concept Introduction:

Phase diagram: In any phase diagram, the thick lines indicate the equilibrium existing between two phases. In the given phase diagrams, the very 1^st phase from the top is the solid phase and the next adjacent phase is the liquid phase. The phase below the liquid phase is the gaseous phase which will be the bottom portion of the entire phase diagram.

Defining Sublimation:

Sublimation is the process of transformation of a solid phase to its gaseous phase directly without undergoing into the intermediate liquid phase.

(e)

Interpretation Introduction

Interpretation:

In the given phase diagram, the number of triple points have to be identified.

Concept Introduction:

Phase diagram: In any phase diagram, the thick lines indicate the equilibrium existing between two phases. In the given phase diagrams, the very 1^st phase from the top is the solid phase and the next adjacent phase is the liquid phase. The phase below the liquid phase is the gaseous phase which will be the bottom portion of the entire phase diagram.

Defining triple point:

In the phase diagram, the triple point is the point at which all the three phases of a substance exist in equilibrium.