A phase is:

A region in a system, of uniform or uniformly varying properties, bounded by a surface, where properties change abruptly.
A substance in a system, produced by any equilibrium reaction in that system.
A physical property of a system, which can be observed or measured.
Any of the chemical substances in a system.
The solid, liquid or gaseous part of a system.
Any process such as boiling, evaporation, condensation, freezing, melting etc.

The number of components of a system is:

The minimum number of chemical substances necessary to define the composition of all parts of the system.
The number of substances in a system, produced by any equilibrium reaction in that system.
The number of chemical substances in a system.
The number of intensive physical properties of a system which can be measured
The number of processes such as boiling, evaporation, condensation, freezing, melting etc. occurring in a system.
The number of solid, liquid or gaseous parts of a system.

A very large stoppered flask contains small amounts of liquid water, ethanol and propanone under nitrogen, at room temperature.
At equilibrium, what is the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

The system in the previous question, is heated until all the liquids evaporate.

At equilibrium, what is the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

A large sealed flask contains 0.1 mole of each of nitrogen, water, hexane, mercury and potassium sulphate, at room temperature. The solubility of K2SO4 in water is approximately 1 mol in 100 moles of water.

At equilibrium, what is the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

The flask in the previous question is heated so that the hexane evaporates.
At equilibrium, what is the new number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

A sample of water is placed in a flask, which is then cooled in liquid nitrogen (to -196(C). All the air is removed by pumping it out, and the flask is sealed and warmed until some (but not all) of the water melts.

At equilibrium, what is the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

A container of adjustable volume is completely filled with a concentrated aqueous solution of KNO3 at 50(C. The volume of the container is increased, so that some liquid evaporates, and the system is cooled until some KNO3 crystallises out.

At equilibrium, what is the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

The mixture in the previous question is further cooled until some of the water freezes.

At equilibrium, what is the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

On the planet Solarus, where the atmosphere is pure carbon dioxide, Capt. Flash Gordon mixes himself an iced gin & tonic in a closed cocktail shaker.

In the shaker, what is the number of:

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

If in the previous question, he had used vodka (assume a pure alcohol/water mixture), water (no tonic) and ice, what would have been the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

Consider the foam on the head of a glass of beer.

What is the number of

phases?

0
1
2
3
4
5
Cannot tell

components?

0
1
2
3
4
5
Cannot tell

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