Topic 2- States Of Matter And Mixtures

Question 1

What is a solid?

Answer 1

• particles have strong forces
• regular lattice arrangement
• particles don’t move; they vibrate on the spot
• not much energy

Question 2

What is a Liquid?

Answer 2

• particles have some forces
• they’re free to move but often stick together
• don’t keep a definite shape
• have more energy than solids

Question 3

What is a gas?

Answer 3

• there’s very little force of attraction
• they’re free to move
• travel in straight lines
• lots of energy

Question 4

What is a physical change?

Answer 4

When a substance changes from one state to another

Eg. A liquid into a gas

Question 5

What is a chemical change?

Answer 5

When bonds between atoms break and the atoms change places

Question 6

What is a pure substance?

Answer 6

A substance is pure if it’s completely made up of a single element or compound

Question 7

How can you use melting point to test if a substance is pure?

Answer 7

• pure substances have specific, sharp melting points

* if a substance isn’t pure it will melt gradually over a range of temperatures

Question 8

How does simple distillation work?

Answer 8

•simple distillation is used for separating out a liquid from a solution

Question 9

What is chromatography?

Answer 9

Chromatography is a method used to separate a mixture of soluble substances and identify them

Question 10

Equation for chromatography

Answer 10

Rf= distance travelled by solute ÷ distance traveled by solvent

Question 11

What are the 3 main sources of water?

Answer 11

• surface water- lakes, reservoirs, rivers
• Ground water- from aquifers(rocks that trap water underground)
• Waste water- water that’s been contaminated by human processes

Question 12

What are the steps to purify water?

Answer 12

• Filtration
• Sedimentation
• Chlorination

Question 13

What is the process of filtration in purifying water?

Answer 13

The water is put through a wire mesh to filter out twigs

Then a sand bed to filter out any other solid bits

Question 14

What is the process of sedimentation in purifying water?

Answer 14

Iron sulphate or aluminium sulphate is added which makes fine particles clump together and settle at the bottom

Question 15

What is the process of chlorination in purifying water?

Answer 15

Chlorine gas is bubbles through to kill harmful bacteria and microbes

Question 16

What is filtration?

Answer 16

Filtration is used to separate an insoluble solid from a liquid.

Question 17

What is crystallisation?

Answer 17

Crystallisation is used to produce solid crystals from a solution.

When the solution is warmed, some of the solvent evaporates leaving behind a more concentrated solution.

Question 18

Mobile phase (chromatography)

Answer 18

Where the molecules can move

This is always a liquid or a gas

Question 19

Stationary phase (chromatography)

Answer 19

Where the molecules can’t move

This can be a solid or a really thick liquid