Chemistry (states of matter)

Question 1

What are the three states of matter?

Answer 1

Solid, liquid, gas.

Question 2

Gas

Answer 2

Arrangement of particles= random, far apart.

Movement of particles= fast in all directions.

Question 3

Liquid

Answer 3

Arrangement of particles= random, close together

Movement of particles= move around each other.

Question 4

Solid

Answer 4

Arrangement of particles= regular and close together

Movement of particles= vibrate around a fixed position.

Question 5

State changes

Answer 5

Are physical changes. They can be reversed and the chemical properties of the substance do not change.

Question 6

Chemical changes-

Answer 6

Different to physical changes.
Happen during a chemical reaction, when bonds between atoms break and the atoms change places.
Hard to reverse.

Question 7

Melting point

Answer 7

Below the melting point, the substance is solid.

Question 8

Melting and boiling point-

Answer 8

The substance is a liquid.

Question 9

Above boiling point-

Answer 9

The substance is a gas.

Question 10

Pure-

Answer 10

A substance is pure if it’s completely made up of a single element or compound.
A pure substance cannot be changed and is the same in all parts of a piece of the substance.

Question 11

Mixture-

Answer 11

A mixture contains elements and/or compounds that are not chemically joined together. You can use physical processes to separate mixtures into different substances.

Question 12

Testing for purity using melting points-

Answer 12

Every pure substance has a specific melting point and boiling point. Impure substances will melt over a range of temperatures.

Question 13

Distillation-

Answer 13

Is used to separate mixtures that contain liquids.

There are two types that you need to know about- simple and fractional.

Question 14

Crystallisation-

Answer 14

A solution is a mixture made of solutes in a liquid called the solvent. Solutes can be separated from a solution by evaporating the solvent to leave the solute behind.

Question 15

Filtration-

Answer 15

If the product of a reaction is an insoluble solid, you can use filtration to separate it out from the liquid reaction mixtures.

Question 16

What happens in a risk assessment?

Answer 16

The hazards of an experiment are identified.

Question 17

Chromatography-

Answer 17

Can be used to find out which coloured compounds the mixture contains.
A method used to separate a mixture of soluble substances and identify them. There are two phases.

Question 18

A mobile phase-

Answer 18

Where the molecules can move. This is always a liquid or a gas.

Question 19

A stationary phase-

Answer 19

Where the molecules can’t move. This can be a solid or a really thick liquid.

Question 20

Rf value

Answer 20

Rf= distance moved by the spot divided by the distance moved by the solvent.

Question 21

Paper chromatography can be used to:

Answer 21

Distinguish between pure and impure substances
Identify substances by comparing the pattern on the chromatography with the patterns formed by known substances.
Identify substances calculating their Rf values.

Question 22

Fractional distillation can be used:

Answer 22

To separate the different products in crude oil
To make alcoholic drinks such as whisky and vodka
To spectate out the gases in the air, after the air has been cooled and turned into a liquid at -200 degrees.

Question 23

Filtration-

Answer 23

A wire mesh screens out large twigs etc., And then gravel and sand beds filter out any other solid bits.

Question 24

Sedimentation-

Answer 24

Iron surface or aluminium sulfate is added to the water, which makes fine particles clump together and settle at the bottom.

Question 25

Chlorination-

Answer 25

Chlorine gas is bubbles through to kill harmful bacteria and other microbes.