03 Changes of States of Matter

Question 1

Describe how heat changes the state of matter.

Answer 1

When a solid/liquid is heated, the particles gain energy = start vibrating faster and faster = until enough energy to break free from their fixed positions/break free from the forces of attraction between the particles and molecules.

When a gas/liquid is cooled, the particles lose energy and move and vibrate slower and slower. The particles no longer can overcome the forces of attraction and move very close together (liquid) or get stuck in a fixed position (solid).

Question 2

Define “vaporisation”.

Answer 2

Change of state from liquid to gas

Question 3

Name and define the 2 types of vaporisation.

Answer 3

Evaporation: Takes place at the surface of the liquid -> energy is removed. The particles near the surface can overcome the forces of attraction holding the liquid together and it moves into the space above. Can occur at any temperature.

Boiling: Occurs throughout the liquid, but only at boiling point.

Question 4

Define “condensation”.

Answer 4

Change of state from gas to liquid. When a gas is cooled to and below its boiling point.

Question 5

Define “melting”.

Answer 5

Change of state from solid to liquid. When a substance melts, its called the melting point.

Question 6

Define “freezing”.

Answer 6

Change of state from liquid to solid. Occurs when a liquid is cooled to and below its freezing point.

Question 7

Define “sublimation”.

Answer 7

Change of state directly from solid to gas, without going through the liquid phase.

Question 8

Define “deposition”. (NOT Geography)

Answer 8

Change of state directly from gas to solid, without going through the liquid phase.

Question 9

Describe how one can test if a substance is pure or not.

Answer 9

Every substance has its own unique melting point, boiling point and freezing point.

If a substance, for example, melts over a range of temperatures, then it is not pure and it is a mixture of materials. If it only melts at one specific temperature, then the substance is pure.

Question 10

Define “brownian motion”.

Answer 10

Random motion of particles suspended in a fluid (liquid/gas) resulting from their collision with fast moving atoms or molecules in the gas or liquid.

Question 11

Define “diffusion”.

Answer 11

Movement and mixing of particles, from a high to a low concentration. The more energy the particles have, the quicker it will diffuse.