year 9 term 1

Question 1

Mixture

Answer 1

2 or more substances that are not chemically bonded and can be separated by physical processes

Question 2

Pure substance

Answer 2

a pure substance has the same fixed components in all its parts, so it cannot be separated into other substances using physical methods i.e. filtering
they are either a element or a compound.

Question 3

filtration

Answer 3

filtration is when you separate mixtures

Question 4

chromotography

Answer 4

separates liquids of different colors

some inks or insoluble in water but if you use a different solvent it might work

Question 5

distillation

Answer 5

separates liquids with different boiling points

Question 6

evaporation

Answer 6

seperates a liquid and a solid by boiling of the liquid

Question 7

soluble

Answer 7

a substance that can be dissolved

Question 8

retention factor (Rf)

Answer 8

it is the ratio of the distance traveled bu the sample (spot of ink) to the distance travelled by the solvent

Question 9

Retention factor formula (Rf)

Answer 9

Rf= distance moved by sample
———————————————
distance moved by solvent

Question 10

residue

Answer 10

what gets left behind in filter paper

Question 11

crystallisation

Answer 11

we can separate a solute from a solution by evaporating a solvent to leave the solutes behind

Question 12

solute

Answer 12

solid

Question 13

solvent

Answer 13

liquid

Question 14

solution

Answer 14

solid+liquid

Question 15

evaporating basin

Answer 15

water is held in this for evaporation/crystilisation

Question 16

hazard

Answer 16

something that can cause harm

Question 17

risk

Answer 17

chance of something happening

Question 18

when is a solution said to be saturated

Answer 18

a solution is saturated when no further solute may be dissolved in the solvent at a fixed temperature and volume of solvent

Question 19

the melting point of gallium is 29.8C and its boiling point is 2204C predict its state at 25C 100C and 2205C

Answer 19

solid at 25C
liquid at 100C
gas at 2205C

Question 20

propanone is a flammable solvent. a student carries out paper chromatography of ink using propanone. identify the mobile phase and the stationary phase in her experiment. explain one necessary precaution. suggest why propanone should be below the ink spot on the paper at the start.

Answer 20

mobile phase: propanone
stationary phase: paper Avoid flames because propanone is flammabe. the ink would dissove into the propanone / wash out the paper

Question 21

two dyes have the same Rf values when tested using paper chromatography. Explain whether this mean they are the same dye or not.

Answer 21

it could be either. they moved the same distance so they could be the same or they could be similar

Question 22

explain why simple distillation allows a pure solvent to be separated from a solution

Answer 22

solvent has a lower boiling point than the solute / solvent is liquid, but solute is solid at room temperature. solvent boils and leaves solution. solvent vapour is cooled and condensed away from the solution.