SC1 & SC2

Question 1

What is the arrangement and movement of particles in gas?

Answer 1

Arrangement: random and far apart
Movement: fast in all directions

Question 2

What is the arrangement and movement of particles in liquid?

Answer 2

Arrangement: random and close together
Movement: move around each other

Question 3

What is the arrangement and movement of particles in a solid?

Answer 3

Arrangement: regular and close together
Movement: vibrate about fixed positions

Question 4

What’s the process that turns gas into a liquid?

Answer 4

Condensing

Question 5

What’s the process that turns a liquid into a solid?

Answer 5

Freezing

Question 6

What’s the process that turns a gas into a solid?

Answer 6

Depostion

Question 7

What’s the process that turns a solid into a gas?

Answer 7

Sublimation

Question 8

What’s the process that turns a solid into a liquid?

Answer 8

Melting

Question 9

What’s the process that turns a liquid into a gas?

Answer 9

Evaporation and boiling

Question 10

How do you know the state of a substance using its temperature, melting point and boiling point?

Answer 10

If the temperature is…
Below the melting point= solid
Between the melting point and boiling point= liquid
Above the boiling point= gas

Question 11

What is the composition of a pure substance?

Answer 11

Can’t be changed

Is the same in all parts of a piece of the substance (e.g. pure gold contains only gold atoms)

Question 12

What is a mixture?

Answer 12

A mixture contains elements and/or compounds that aren’t chemically joined together
They don’t have fixed, sharp melting points

Question 13

What is crystallisation?

Answer 13

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

Question 14

What is evaporation?

Answer 14

Pour solution in evaporating dish and slowly heat it so the solvent will evaporate
Reaches point where there is as much salt in water as can possibly dissolve (saturated solution)
Water evaporates and solute leaves the solution and salt crystals form

Question 15

What is filtration?

Answer 15

Filter funnel is lined with filter paper and, when solvent and solute are poured through, the solid is left in the paper
A Bunsen burner is used to evaporate the filtrate

If the solution is over heated once saturated, hot crystals could spit out

Question 16

What is paper chromatography?

Answer 16

Chromatography is used to find out which coloured compounds the mixture contains

When solvent moves along paper, it carries different substances at different speeds in mixture so they’re separated

Question 17

How do you do paper chromatography?

Answer 17

Draw pencil line and ass a spot of ink to the line and place paper in a beaker of water (ink shouldn’t touch the solvent)
Solvent seeps up the paper with the ink and each different dye will move up at different speeds, separating out
If the dyes are insoluble, they’ll stay at the base line

Question 18

How do you work out the Rf?

Answer 18

Rf= distance moved by spot / distance moved by the solvent

Rf values are always led than 1

Question 19

What is distillation?

Answer 19

Distillation is used to separate mixtures which contain liquids

Question 20

What is simple distillation?

Answer 20

Used to separate a liquid from a solution

Solution is heated and the part of solution that has the lowest boiling point evaporates first
The vapour is then cooled, condenses and is collected
The rest of the solution is left in the flask

Question 21

What is fractional distillation?

Answer 21

Used to separate a mixture of liquids

Mixture is heated and hot vapour rises up the fractionating column but drips back down the flask when it hits the cool glass and condenses
As column heats up, will be a temperature gradient (hottest at bottom) so the fraction will lowest boiling point will reach the” top first and pass into condenser. If heating continues, fractions with higher boiling points will rise up column and be collected

Question 22

How do you make water potable?

Answer 22

Water must be filtered to remove solid impurities
Sedimentation is used to allow smaller objects (sand) to settle out of the water
Water is then passed through sand and gravel
Chlorination kills microorganisms in the water
Drinking water then stored in towers and transported to homes and industry