Topic 2 - States of Matter and Mixtures

Question 1

What are the three states of matter?

Answer 1

• Solid
• Liquid
• Gas

Question 2

What does the state a material is in depend on?

Answer 2

How strong the force of attraction is between the particles of the material (the atoms, ions or molecules)

Question 3

What is the strength of forces between particles determined by?

Answer 3

• Temperature
• Pressure
• The material (the structure of the substance and the type of bonds holding the particles together)

Question 4

What are the characteristics of a solid?

Answer 4

• Compact, close together, fixed arrangement
• Particles vibrate around a fixed position
• Particles have low kinetic energy

Question 5

What are the characteristics of a liquid?

Answer 5

• Particles are close together, randomly arranged
• They flow (slide past each other)
• Particles have ‘between high and low’ kinetic energy

Question 6

What are the characteristics of a gas?

Answer 6

• Spread out, spaced, don’t touch
• Totally random arrangement
• Move freely and constantly at lots of speed
• Particles have high kinetic energy

Question 7

What is the process of a solid to liquid?

Answer 7

Fusion (Melting)

Question 8

What is the process of a liquid to gas?

Answer 8

Evaporation

Question 9

What is the process of gas to liquid?

Answer 9

Condensation

Question 10

What is the process of liquid to solid?

Answer 10

Freezing

Question 11

What is the process of gas to solid?

Answer 11

Deposition

Question 12

What is the process of solid to gas?

Answer 12

Sublimation

Question 13

When does evaporation occur?

Answer 13

Evaporation occurs at all temperatures because some of the particles in a liquid have a high enough energy to overcome the forces of attraction. If they reach the surface of the liquid, these particles can then escape to become particles of a gas. As these high energy particles leave, the remaining liquid has less thermal energy so it cools down. This is why sweating helps to keep you cool.

Question 14

When does boiling occur?

Answer 14

Boiling occurs when an external heat source transfers thermal energy to the liquid causing it to reach and maintain its boiling point. This causes all particles, throughout the liquid, to have a high enough energy to overcome attractive forces to become particles of a gas. This is why bubbles form.​

Question 15

Is a physical or chemical change reversible?

Answer 15

Physical change

Question 16

What happens when a solid, liquid or gas cool?

Answer 16

The kinetic energy of the particles decrease, which means the temperature also decreases

Question 17

What happens during a change of state?

Answer 17

The kinetic energy of the particles stays constant, which means the temperature also stays constant.
Thermal energy is transferred to the surroundings due to the forces of attraction that are formed between particles.
This occurs at the same rate as energy is being removed by cooling – so the temperature does not change.​

Question 18

What is a pure substance?

Answer 18

A sample of matter with both definite and constant composition and distinct chemical properties

Question 19

What is a mixture?

Answer 19

More than two different substances that are not chemically joined together. The substances can be separated by physical processes.

Question 20

What is an element?

Answer 20

A simple substance formed of only one type of atom.​

Question 21

What is a compound?

Answer 21

Formed of more than one type of atom chemically bonded together. They can be chemically split into simpler substances.​

Question 22

What is pure?

Answer 22

One type of element or compound. It cannot be changed and is the same in all parts of the substance.​

Question 23

What is a pure compound?

Answer 23

Formed of more than one type of atom chemically bonded together and shaped in the same way. They can be chemically split into simpler substances.​

Question 24

What is an alloy?

Answer 24

A mixture of a metal

Question 25

What is saturated?

Answer 25

When no more solute can dissolve in a solution

Question 26

What is solubility?

Answer 26

A measure of how much dissolves (g per 100g)

Question 27

What is a solute?

Answer 27

The substance which dissolves in a solution

Question 28

What is a solution?

Answer 28

A mixture of a solute and a solvent.

Question 29

What is a solvent?

Answer 29

A liquid which dissolves a solute

Question 30

How is filtration done?

Answer 30

1) Fold a piece of filter paper into the shape of a cone
2) Put the filter paper into the filter funnel
3) Pour the mixture containing the insoluble solid into the funnel. The solid should get left behind, and the liquid would have passed through the funnel

Question 31

How is cystallisation done?

Answer 31

1) Place an evaporating dish on top of a tripod, with a heat proof mat. Place the bunsen burner underneath.
2) Pour the solution into the dish and gently heat it
3) Once some of the water has evaporated, some crystals should start to form. Remove the dish from the heat, and leave to cool
4) The dissolved compound should start to form crystals, as it becomes insoluble in the cold, high concentrated solution
5) Filter the crystals out of the solution, and leave them in a warm place to dry

Question 32

What is chromatography?

Answer 32

A method to separate a mixture of soluble substances and identify them

Question 33

What is a mobile phase?

Answer 33

Where the molecules can move

Question 34

What is a stationary phase?

Answer 34

Where the molecules cannot move

Question 35

How do you carry out paper chromatography?

Answer 35

1) Check that your chromatography paper hangs close to the bottom of the empty beaker without touching it
2) Take the paper out of the beaker and draw a pencil line on the paper, about 2 cm from the bottom. Put a small spot of ink on your pencil line.
3) Pour some water into the beaker to a depth of about 1 cm.
4) Lower the chromatography paper into the beaker so that the bottom of the paper is in the water, but the water level is below the spots.
5) Leave the paper in the beaker until the water reaches near the top of the paper.
6) Take the paper out and immediately use a pencil to mark the location of the solvent front (the level the water has reached) before it evaporates. Leave it to dry.

Question 36

How do you calculate the Rf value?

Answer 36

Rf value = distance travelled by solute (B) ÷ distance travelled by solvent (A)

Question 37

What is simple distillation?

Answer 37

Used to separate a solvent from a solution, with boiling points, which aren’t close to each other.

Question 38

What happens if the boiling points in simple distillation are close to each other?

Answer 38

The simple distillation doesn’t work. The temperature may rise above the boiling point of more than one of the substances, and they’ll end up mixing again.

Question 38

How do you carry out simple distillation?

Answer 38

1) Put the distillation flask on a tripod on a heat mat. Put a bunsen burner under the tripod the distillation flask, and place a condenser on top.
3) Place a beaker under the other end of the condenser, for the pure water to come out.
4) Turn the bunsen burner on, with the air hole half open, so there is a blue flame. The gas should also be half on.
5) Heat the liquid until it boils
6) Collect the distillate in the test tube and note the temperature of the vapour

Question 39

How do you carry out fractional distillation?

Answer 39

1) Put the distillation flask on a tripod on a heat mat. Put a bunsen burner under the tripod. Fill the distillation flask up with the liquid.
2) Place a fraction column on top, with a thermometer, along with the condenser
3) Put boiling tubes in a rack, under the condenser, each boiling tube, for a different temperature - the liquids all have different temperatures, so they’ll evaporate at different times.
4) The liquid with the lowest boiling point evaporates first. When the
temperature on the thermometer matches the boiling point of this
liquid, its vapour has reached the top of the column and passed into the
condenser. It will then cool and condense and run out of the end.
The pure liquid can then be collected.
5) Liquids with higher boiling points might also start to evaporate. But the
column is cooler towards the top. So they will only get part of the way up
before condensing and running back down towards the flask.
6) When the first liquid has been collected, you raise the temperature to the
next lowest boiling point of the liquids in the mixture.

Question 40

How do you treat groundwater?

Answer 40

1) Water is stored ready for distribution​
2) Screening-to remove large object​
3) To our taps
4) pH check and Chlorination - to kill bacteria and viruses​
5) Sedimentation: solids sink (and are left behind)
6) Coagulation: alum is added to clump together small bits of dirt. ​Further sedimentation.​
7) Filtration: very small particles are removed.

Question 41

How do you treat sea water?

Question 42

How do you treat ground water?