Topic 2

Question 1

chlorination reason

Answer 1

to kill microorganisms

Question 2

why is a sample of water potable even though it contains impurities

Answer 2

the impurities are harmless

Question 3

solid to gas

Answer 3

sublimation

Question 4

compared to physical changes

Answer 4

chemical changes are hard to reverse

Question 4

pure

Answer 4

made up of a single compound

Question 5

you can test for purity by finding the boiling point

Answer 5

if its a substance it wont have one expected value, the mixture will gradually evaporate over a range of temperatures

Question 6

what can you use to mesure the melting point

Answer 6

metal point apparatus

Question 7

simple distillation

Answer 7

separating a liquid from a solution

Question 8

fractional distillation

Answer 8

sepearting many liquids with similar boiling points

Question 9

diagram

Answer 9

water out, in

Question 10

simple distillation

Answer 10

the substance with the lowest boiling point will evaporate first, reach the condensing tube and condense as it cools, goes down the tube into the beaker

Question 11

if boiling points are very similar

Answer 11

multiple rounds of distillation

Question 12

why are there glass beads in fractional distillation

Question 13

mobile phase

Answer 13

liquids/ gas can move

Question 14

imobile phase

Answer 14

solid or very viscous liquid

Question 15

imobile phase

Answer 15

solid or very viscous liquid

Question 16

draw a pencil line

Answer 16

the ink form a pen may move up
pencil is insoluble in solvent

Question 17

value of chemical

Answer 17

distance traveled by solute/ solvent

Question 18

sea water

Answer 18

very expensive to distill as requires alot of energy

Question 19

Which row of the table shows these three processes in the order in which they are carried
out?

Answer 19

sedimentation, filtration, chlorinisation

Question 20

Describe how sedimentation is carried out.

Answer 20

put water in a tank and leave it to settle, impurities fall to the botttom

Question 21

State what could be changed in the experiment to make the Rf value more accurate.

Answer 21

use longer paper

Question 22

In this experiment, ink sample Y did not move from the start line.
Explain a change to the experiment that would be needed to separate the dyes in ink
sample Y.

Answer 22

use different solvent to ink will dissolve

Question 23

The liquid collected in the beaker is known as the

Answer 23

distillate

Question 24

Describe how a sample of pure, dry sodium chloride crystals can be obtained from the filtrate.

Answer 24

heat, leave on a radiator, pat dry with a cloth, scrape crystals from container

Question 25

Explain how the water in sea water separates to produce the pure water in this apparatus.

Answer 25

use a liebig condencer with col wae so all the water vapour condenses, increased effectiveness of cooling

Question 26

Name the piece of equipment labelled X in Figure 6.

Answer 26

delivery tube

Question 27

Explain why it is important that the water used is pure.

Answer 27

ions would interefere results, pure water has no ions

Question 28

(i) Identify the stationary phase in this experiment.

Answer 28

water in the paper

Question 29

Give a reason why the spots of the food colourings must be above the level of the solvent, when the paper is placed in the solvent.

Answer 29

so that the solvent will run through spots

Question 30

Give the reason why the spot of food colouring V has not moved during the chromatography experiment.

Answer 30

V is insoluble in this solvent

Question 31

Explain, by referring to Figure 11, which food colouring contained the greatest number of soluble, coloured substances.

Answer 31

Z, it has teh most spots