Two-Component Solid/Liquid Systems

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Questions and Answers

What is the number of degrees of freedom for the system ice-water-vapour at the triple point?

0 (correct)

What is the effect of an increase in pressure on the melting point of ice?

It has no effect on the melting point

It increases the melting point

It decreases the melting point (correct)

It has a varying effect on the melting point

What is the condition for a system to be monovariant?

It has three phases and two components

It has two phases and two components

It has one phase and two components

It has two phases and one component (correct)

What is the significance of the triple point 'O' in the phase diagram?

It represents the equilibrium of three phases: liquid water, ice, and vapour Signup and view all the answers

What is the role of Le Chatelier's principle in the phase diagram?

It states that the melting point of ice decreases with an increase of pressure Signup and view all the answers

What is the condition for a system to be nonvariant?

It has three phases and one component Signup and view all the answers

What is the number of degrees of freedom in a one-phase and one-component system?

2 Signup and view all the answers

What do the areas AOC, AOB, and BOC represent in the phase diagram?

The conditions for stable existence of one phase Signup and view all the answers

What is the normal melting point of ice at 1.0 atmosphere?

0°C Signup and view all the answers

What is the term used to describe the supercooled water/vapour system?

Metastable system Signup and view all the answers

What is the temperature at which the two solid polymorphic forms of sulphur, SR and SM, are in equilibrium?

95.6°C Signup and view all the answers

What is the number of phases in the sulphur system represented in the phase diagram?

4 Signup and view all the answers

What is the term used to describe the point at which the three phases of water, ice, and water vapour coexist in equilibrium?

Triple point Signup and view all the answers

What is the state of the system when it has two phases, such as water and water vapour?

Univariant Signup and view all the answers

What is the process by which the supercooled water/vapour system reverts to the stable system ice/vapour?

Phase transition Signup and view all the answers

What is the term used to describe the relationship between the two solid polymorphic forms of sulphur, SR and SM?

Enantiotropy Signup and view all the answers

What is the degree of freedom at the equilibrium represented by the curve AC?

1 Signup and view all the answers

What is the significance of the point C in the phase diagram?

Both A and B are in equilibrium with the solution phase. Signup and view all the answers

What is the number of phases at the point C in the phase diagram?

3 Signup and view all the answers

What is the effect of adding B to A on the freezing point of A?

It decreases the freezing point of A. Signup and view all the answers

What type of system is represented by the phase diagram in Figure 19.5?

Simple Eutectic System Signup and view all the answers

What is the degree of freedom at the point C in the phase diagram?

0 Signup and view all the answers

What is the phase transition that occurs when the system moves from the curve AC to the point C?

Liquid solution to solid A and solid B Signup and view all the answers

What is the difference between the curves AC and BC in the phase diagram?

Curve AC represents the freezing point of A, while curve BC represents the freezing point of B. Signup and view all the answers

Study Notes

Simple Eutectic Systems

A 2-component condensed system has a phase diagram consisting of a Temperature-Concentration graph (TC graph)
The diagram shows the freezing point curves of two components A and B, which are completely miscible in the liquid state
The curves intersect at the eutectic point C, where both solids A and B are in equilibrium with the solution phase

Freezing Point Curves

Curve AC: Freezing point curve of A, where the freezing point of A falls with the addition of B
Curve BC: Freezing point curve of B, where the freezing point of B falls with the addition of A

Eutectic Point

The eutectic point C is where the two curves AC and BC meet
At point C, both solids A and B are in equilibrium with the solution phase
The system has 3 phases: solid A, solid B, and the solution
Applying the reduced phase rule equation, the degree of freedom is 0, making the system nonvariant

One-Phase Systems

Area AOB represents the one-phase system water vapour
Area BOC represents the one-phase system ice
Each system has 2 degrees of freedom
The system is bivariant

Metastable System: Supercooled Water/Vapour System

Water can be supercooled by carefully eliminating solid particles
The supercooled water/vapour system is metastable (unstable)
It reverts to the stable system ice/vapour on disturbance or introduction of a crystal of ice

Polymorphic Forms of Sulphur

Two solid polymorphic forms of sulphur: Rhombic Sulphur (SR) and Monoclinic Sulphur (SM)
SR is stable below 95.6°C, while SM is stable above 95.6°C
At 95.6°C, each form can be gradually transformed to the other and the two are in equilibrium

Phase Diagram of Sulphur System

The phase diagram shows the enantiotropy of sulphur
The diagram has four phases: two solid polymorphic forms (SR and SM), sulphur liquid (SL), and sulphur vapour (SV)

Phase Diagram of Water

The phase diagram shows the effect of pressure on the melting point of ice
The melting point of ice decreases with an increase in pressure
The triple point is the point where all three phases (liquid water, ice, and vapour) are in equilibrium

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Description

Learn about the phase diagrams of two-component condensed systems, including simple eutectic systems and their temperature-concentration graphs.