paper 6

Question 1

suggest why an excess of sodium sulfate is added to the water in the beaker

Answer 1

to ensure a saturated solution is formed

Question 2

suggest why the mixture in the beaker was stirred as it was heated

Answer 2

to speed up reaction

Question 3

explain why the temperature change decreases towards the end of each expirment

Answer 3

solution has been used up

Question 4

explain why the results obtained would be different if a polystyrene cup is used instead of the beaker

Answer 4

temp is higher, less heat is lost to surroundings

Question 5

explain an advantage and disadvantage of using a burette instead of measuring cylinder

Answer 5

more accurate readings
takes more tie to add solution

Question 6

color of metals

Answer 6

grey

Question 7

color copper

Answer 7

brown

Question 8

copper oxide

Answer 8

black

Question 9

copper salts color

Answer 9

blue except copper carbonate green

Question 10

mineral acids and alkalis

Answer 10

colourless

Question 11

hydrocarbos burn

Answer 11

with smoky flame

Question 12

nitrogen dioxide

Answer 12

brown gas

Question 13

barium sulfate

Answer 13

white ppt

Question 14

spatula

Answer 14

scoop powder

Question 15

burette and volumetric pippete

Answer 15

more accurate
slower to add solution
pipette only 25 cm3 possible

Question 16

measuring cyclinder

Answer 16

faster measurments less accurate

Question 17

why is crystalisation used

Answer 17

seperate soluble solids from solution

Question 18

why is oil bath used in fractona distillation

Answer 18

if solution has boiling point higher than water

Question 19

how can you produce solbule salts

Answer 19

titration or acid and excess solid

Question 20

insolbule salts

Answer 20

precipitation

Question 21

white tile titration

Answer 21

more vivid color change

Question 22

litmus paper

Answer 22

red acid, blue alkaline

Question 23

phenolthalein

Answer 23

pink acid, blue alkaline

Question 24

methyl orange

Answer 24

red acid, yellow alkaline

Question 25

how can you collect gas with water danger

Answer 25

if gas insoluble in water
if heating remove delivery tube first to avoid cracking

Question 26

why is sukfuric acid used

Answer 26

to dry gas except ammonia

Question 27

why dont you over heat crystallisation

Answer 27

not produce dry powder salt, as you want hydrated salts

Question 28

crystalisation point

Answer 28

place galss rod, crystals formed

Question 29

precipitation why do you put water

Answer 29

insoluble= remove soluble impuraties
soluble= collect all salt

Question 30

cotton wool why used

Answer 30

allow gas to leave
avoid spilling of acid