Unit 1

Question 1

What is random motion?

Answer 1

When particles move and they collide with each other and bounce off in all directions

Question 2

What is diffusion

Answer 2

In 2 substances, when mixed, particles bounce off in all directions when they collide. The mixing process is called diffusion.

Question 3

What is a molecule?

Answer 3

The particles consist of 2 atoms joined together. A group of atoms held together by covalent bonds.

Question 4

What is an ion?

Answer 4

Particles that consist of atoms or groups of atoms that carry a charge.

Question 5

What are solid properties?

Answer 5

Definite shape and volume
Normally hard and rigid 
Large force required to change shape 
High density 
Incompressible

Question 6

What is the model of solids?

Answer 6

Closely packed 
Occupy minimum 
regular pattern 
Vibrate in fixed position 
Not free to move

Question 7

What are the liquid properties?

Answer 7

Definite model but no shape
High density
Not compressible

Question 8

What’s the model of liquid?

Answer 8

Occur in clusters with molecules further apart compared to solids
free to move about within a confined vessel

Question 9

What are the gas properties?

Answer 9

No fixed volume and no fixed shape
Low density
Compressible

Question 10

What’s the model of gas?

Answer 10

Very far apart
Travel at high speed
Independent and Random motions
Negligible forces of attraction between them

Question 11

Why does the lower mass of particles , the faster the gas diffuses?

Answer 11

Because the lighter the molecules, the faster it will travel

Question 12

Why the higher the temperature, the faster a gas will diffuse?

Answer 12

Because particles gain energy as they are heated

Question 13

What is a mixture?

Answer 13

Substance that contains more than one substance. They are just mixed together and not chemically bonded. E.g sand and water

Question 14

What is a solution?

Answer 14

It is when a solute and a solvent mix. The solute dissolves in the solvent making a solution. E.g sugar (solute) dissolves in water (solvent) making a solution of sugar and water

Question 15

How can you help a solvent dissolve?

Answer 15

Stir it

Rise the temperature

Question 16

What does saturated mean ?

Answer 16

Cannot dissolve anymore. If you put an excess amount of sugar in a small amount of water it will not dissolve as there is no place for it. It becomes saturated

Question 17

What is a solvent?

Answer 17

A substance that allows solute to dissolve in e.g water , ethanol

Question 18

What is a pure substance?

Answer 18

A substance that has no particles of any other substance mixed with it

Question 19

What is an impurity?

Answer 19

An unwanted substance , mixed with a wanted substance

Question 20

How can you check if a substance is pure?

Answer 20

Check it’s melting and boiling points

Question 21

Attributes of a pure substance?

Answer 21

Has a definite, sharp , melting point

Question 22

Attributes of an impure substance?

Answer 22

The melting point falls and its boiling point rises. So he more impurity present, the wider and bigger the change in melting and boiling point

Question 23

What is centrifuging?

Answer 23

The method is used to separate small amount of solid and liquid. Inside the centrifuge (it’s a machine), test tubes are spun very fast so the solid gets flung to the bottom.

Question 24

What is crystallisation?

Answer 24

This method is similar to evaporation but here the solid forms crystals then the crystals are left to dry

Question 25

What is simple distillation?

Answer 25

The impure liquid is heated
It boils and steam rises into the condenser
The impurities are left behind
The condenser is cold so the steam condenses to the pure liquid and it drops out

Question 26

What is fractional distillation?

Answer 26

The mixture is heated
The wanted substance boils and evaporates(some of the unwanted liquid will evaporate too) and rises up the column
This substance will condense on the beads in the column causing them to heat
When the beads reach a certain temperature when the wanted liquid won’t condense anymore(that’s the boiling point) it will rise while the unwanted liquid will condense and drop . the wanted liquid will make its way through the condenser where it will condense and drop down into the beaker

Question 27

What is a chromatogram?

Answer 27

The filter paper showing the separate substances

Question 28

What is chromatography?

Answer 28

The method is used to separate a mixture of substances e.g to find how many coloured substances there are in black ink.

Question 29

What are the uses of chromatography?

Answer 29

Separate mixtures of substances
Purify a substance by separating the impurities from it
Or to identify a substance

Question 30

Brownian motion

Answer 30

The random movement of small visible particles in suspension caused by the un-equal random bombardment of molecules of gas or liquid on the visible particles.