States Of Matter

Question 1

What are the three states of matter?

Answer 1

Solids, liquids and gases

Question 2

When do different state changes of a substance occur?

Answer 2

Different state changes occur at the melting point and at the boiling point depending in whether the substance is heating up or cooling down.

Question 3

Describe the properties of a solid

Answer 3

The arrangement of particles are at a regular arrangement, the movement of particles: vibrate about a fixed position and closeness of particles is very close.

Question 4

Describe the properties of a liquid

Answer 4

The arrangement of particles are randomly arranged, the movement of particles: move around each other and closeness of particles is close.

Question 5

Describe the properties of a gas

Answer 5

The arrangement of particles are randomly arranged, the movement of particles: move quickly in all direction and closeness of particles is far apart.

Question 6

What does the amount of energy needed to change states depend on?

Answer 6

The amount of energy needed to change states depends on the strength of the forces between the particles.

Question 7

What does it mean if the forces of attraction are strong?

Answer 7

If the forces of attraction are strong, then a lot of energy is needed to overcome them for a state change to occur. Therefore, the stronger the forces between the particles the higher the melting point and boiling point of the substance.

Question 8

What is it called when matter changes from one state to another due to changes in temperature or pressure?

Answer 8

The change is called an interconnection of state.

Question 9

Explain an interconversion of state

Answer 9

It is a physical change involving changes in the forces between the particles of the substances, the particles themselves remain the same, as do the chemical properties of the substances.

Question 10

Are physical changes easy or hard to reverse and why?

Answer 10

Physical changes are relatively easy to reverse as no new substance is formed during interconversions of state.

Question 11

Melting (example of state change)

Answer 11

Solid to liquid

Question 12

Boiling (example of state change)

Answer 12

Liquid to a gas (from below surface as well as at surface)

Question 13

Freezing (example of state change)

Answer 13

Liquid to a solid

Question 14

Evaporation (example of state change)

Answer 14

Liquid to a gas (at surface only)

Question 15

Condensation (example of state change)

Answer 15

Gas to a liquid

Question 16

Sublimation (example of state change)

Answer 16

Solid to a gas

Question 17

Explain melting

Answer 17

Melting is when a solid changes into a liquid. The process requires heat energy which transforms into kinetic energy, allowing the particles to move. It occurs at a specific temperature known as the melting point which is unique to each solid.

Question 18

Explain boiling

Answer 18

Boiling is when a liquid changes into a gas. This requires heat which causes bubbles of gas to form below the surface of a liquid, allowing for liquid particles to escape from the surface and from within the liquid. It occurs at a specific temperature known as the boiling point which is unique to each liquid.

Question 19

Explain freezing

Answer 19

Freezing is when a liquid changes into a solid. This is the reverse of melting and occurs at exactly the same temperature as melting, hence the melting point and freezing point of a pure substance are the same. It requires a significant decrease in temperature (or loss of thermal energy) and occurs at a specific temperature which is unique for each pure substance.

Question 20

Explain evaporation

Answer 20

When a liquid changes into a gas. Evaporation occurs only at the surface of liquids where high-energy particles can escape from the liquid surface at low temperatures, below the boiling point of the liquid. The larger the surface area and the warmer the liquid/surface, the more quickly a liquid can evaporate. Evaporation occurs over a range of temperatures, but heating will speed up the process as particles need energy to escape from the surface.

Question 21

Explain condensation

Answer 21

When a gas changes into a liquid, usually on cooling.
When a gas is cooled its particles lose energy and when they bump into each other, they lack energy to bounce away again, instead grouping together to form a liquid.

Question 22

Explain sublimation

Answer 22

When a solid changes directly into a gas.
This happens to only a few solids, such as iodine or solid carbon dioxide.
The reverse reaction also happens and is called desublimation or deposition.

Question 23

Why do we conduct diffusion and dilution experiment?

Answer 23

We conduct these experiments due to the fact that diffusion and dilution experiments support a theory that all matter (solids, liquids and gases) is made up of tiny, moving particles.

Question 24

Explain the diffusion of bromine gas from one gas jar to another

Answer 24

After a few minutes of this diffusion, we can observe that the bromine gas has diffused from the bottom jar to the top jar. This is due to the air and bromine particles moving randomly and there are large gaps between particles
The particles can therefore easily mix together.

Question 25

How does potassium manganate diffuse in water (over water)?

Answer 25

When potassium manganate (VII) crystals are dissolved in water, a purple solution is formed.
A small number of crystals produce a highly intense colour. This is due to the fact that water and potassium manganate (VII) particles are moving randomly and the particles can slide over each other.
The particles can therefore easily mix together.

Question 26

Explain diluting potassium manganate (VII)

Answer 26

When potassium magnate (VII) crystals are dissolved in water, the solution can be diluted several times.
The colour fades but does not disappear until a lot of dilutions have been done. This indicates that there are a lot of particles in a small amount of potassium manganate (VII) and therefore the particles must be very small.