1a. States Of Matter

Question 1

Melting

Answer 1

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 pure solid

Question 2

Boiling

Answer 2

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 pure liquid

Question 3

Freezing

Answer 3

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
Water for example freezes and melts at 0 ºC
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 4

Evaporation

Answer 4

When a liquid changes into a gas
Evaporation occurs only at the surface of liquids where high energy particles can escape from the liquids 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 5

Condensation

Answer 5

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 6

Sublimation

Answer 6

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 7

Solids

Answer 7

Regular particle arrangement
Vibrate about a fixed position
Particles are very close

Question 8

Liquid

Answer 8

Random particle arrangement
Move around each other
Particles are close

Question 9

Gas

Answer 9

Random particle arrangement
Move quickly in all directions
Particles are far apart

Question 10

Solvent

Answer 10

The liquid in which a solita dissolves
Eg. The water in sea water

Question 11

Solute

Answer 11

The substance which dissolves in a liquid to form a solution
Eg. The salt in seawater

Question 12

Solution

Answer 12

The mixture formed when a solute is dissolved in a solvent
Eg. Seawater

Question 13

Saturated solution

Answer 13

A solution with the maximum concentration of solute dissolved in the solvent
Eg. Seawater in the Dead Sea

Question 14

Soluble

Answer 14

Describes a substance that will dissolve
Eg. Salt is soluble in water

Question 15

Insoluble

Answer 15

Describes a substance that won’t dissolve
Eg. Sand is insoluble in water

Question 16

Diffusion in gases

Answer 16

Description:
Here, we see the diffusion of bromine gas from one gas jar to another
After 5 minutes the bromine gas has diffused from the bottom jar to the top jar

Explanation:
The air and bromine particles are moving randomly and there are large gaps between particles
The particles can therefore easily mix together

Question 17

Diffusion in liquids

Answer 17

Description:
When potassium manganate (VII) crystals are dissolved in water, a purple solution is formed
A small number of crystals produce a highly intense colour

Explanation:
The water and potassium manganate (VII) particles are moving randomly and the particles can slide over each other
The particles can therefore easily mix together
Diffusion in liquids is slower than in gases because the particles in a liquid are closely packed together and move more slowly

Question 18

Dilution

Answer 18

Description:
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
Explanation:

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