States of matter

Question 1

What are the three states of matter

Answer 1

Solid, Liquid and Gas

Question 2

Describe the arrangement of particles in solids

Answer 2

Solid particles are close together and touching one another. There are no gaps between them

Question 3

Describe the arrangement of particles in liquids

Answer 3

Liquid particles are close together and touching one another. However, there are some gaps between them

Question 4

Describe the arrangement of particles in gases

Answer 4

Gas particles are far apart with big gaps between them

Question 5

Describe the movement of particles in solids

Answer 5

Solid particles vibrate around their fixed positions and do not move apart

Question 6

Describe the movement of particles in liquids

Answer 6

Liquid particles are in constant, random movement, bouncing off each other

Question 7

Describe the movement of particles in gases

Answer 7

Gas particles move freely and constantly collide with each other at very high speeds

Question 8

What are the conversions between solid and liquid called

Answer 8

Melting (solid to liquid)
Freezing (liquid to solid)

Question 9

What are the conversions between liquid and gas called

Answer 9

Boiling (liquid to gas)
Condensation (gas to liquid)

Question 10

What are the conversions between solid and gas called

Answer 10

Sublimation (solid to gas)
Deposition (gas to solid)

Question 11

Describe the process of melting

Answer 11

The solid is heated and its particles gain kinetic energy and vibrate faster. They start to move further apart and consequently the forces of attraction become weaker. These are no longer strong enough to hold particles in a fixed shape and the solid thus becomes a liquid

Question 12

Describe the process of freezing

Answer 12

The liquid is cooled down and its particles lose kinetic energy and move around more slowly. They eventually come closer together and since the forces of attraction become stronger, the particles are held into fixed positions

Question 13

What does the melting temperature of a solid tell us

Answer 13

The melting temperature gives a measure of how strong the attractive forces holding the particles in the solid together are

Question 14

Why does evaporation occur

Answer 14

Very often particles that have more energy can overcome the forces of attraction holding them together and escape from the surface of the liquid

Question 15

What are the differences between evaporation and boiling

Answer 15

Evaporation takes place at any temperature above the melting point, while boiling takes place only at the boiling point. Also, evaporation takes place only at the surface, while boiling happens throughout the liquid. Lastly, evaporation doesn’t produce bubbles and is a slower process, while boiling is faster and produces bubbles

Question 16

What are the three types of particles that exist

Answer 16

Atoms, molecules and ions

Question 17

What are atoms

Answer 17

Atoms are the smallest particles of an element that exist and can take part in chemical reactions

Question 18

What are molecules

Answer 18

Molecules are the smallest particles of a substance that have all its properties and can exist on their own. It’s made up of atoms held together by covalent bonds

Question 19

What is an ion

Answer 19

An ion is a charged particle formed when an atom gains or loses electrons

Question 20

What is diffusion

Answer 20

Diffusion is the movement of particles from areas of high concentration to areas of low concentration

Question 21

What can affect the rate of diffusion of gases

Answer 21

The mass of the gases involved can affect the rate of diffusion

Question 22

What can you tell about the masses of ammonia and hydrogen chloride gas based on the experiment between them

Answer 22

Ammonia gas is lighter than hydrogen chloride. The white gas formed is closer to the end of hydrogen chloride, indicating that ammonia traveled a greater distance in the same amount of time. This shows that is lighter and was able to diffuse much faster

Question 23

What determines whether a substance dissolves in a solvent

Answer 23

The forces of attraction in the solute and the solvent are broken and new forces are formed between them. If these new forces between the solute and the solvent are stronger than the old ones, then the solute can dissolve

Question 24

What is a saturated solution

Answer 24

A saturated solution is one that can’t dissolve any more solute at a specific temperature

Question 25

Define solubility

Answer 25

Solubility is the mass of a solute which can dissolve in 100g of the solvent at a particular temperature to form a saturated solution

Question 26

What affects the solubility of a solute

Answer 26

The temperature

Question 27

Describe crystallisation

Answer 27

A saturated solution is cooled down, and the solid it can hold thus gets less. The solid that can no longer remain dissolved gradually appears as crystals

Question 28

How does the speed of crystallisation affect the crystals formed

Answer 28

The slower the cooling process, the bigger and purer the crystals formed will be