c6 - electrolysis

Question 1

define electrolysis

Answer 1

• the process that uses electricity to break down ionic compounds into elements
• takes place when electricity passes through a molten ionic compound or solution containing ions

Question 2

define electrolyte

Answer 2

substance broken down in electrolysis

Question 3

define an inert substance

Answer 3

does not react with products

Question 4

what happens when ions reach electrode?

Answer 4

lose their charge and become atoms or molecules

Question 5

what is produced at cathode in molten ionic compount?

Answer 5

metal element

Question 6

what is produced at anode in molten ionic compount?

Answer 6

non-metal

Question 7

why is it difficult to predict what will be formed?

Answer 7

water also forms ions

Question 8

what do positively charged ions form?

Answer 8

hydrogen or metal

Question 9

what do negatively charged ions form?

Answer 9

oxygern (and water) or halogens

Question 10

PANIC

Answer 10

Positive Anode Negative Is Cathode

Question 11

what happens when positively charged ions reach cathode?

Answer 11

gain electrons to become neutral

Question 12

what happens when negatively charged ions reach anode?

Answer 12

• lose electrons to become neutral atoms
• some combine to form molecules e.g bromine Br2

Question 13

give half equation for lead bromine at cathode

Answer 13

Pb(2+) + 2e(-) -> Pb

Question 14

give half equation for lead bromine at anode

Answer 14

2Br(-) -> Br(2) + 2e(-)

Question 15

give two ions in water

Answer 15

H(+) and OH(-)

Question 16

what will be produced at cathode in electrolysis in water?

Answer 16

less reactive element usually formed

Question 17

what happens when aqueous solutions are electrolysed

Answer 17

• positively charged metal ions and H(+) ions attracted to negative electrode
• hydrogen gas produced if hydrogen is less reactive than metal

Question 18

what happens at cathode in electrolysis of aqueous solutions?

Answer 18

2H(+) + 2e(-) -> H(2)(g)

Question 19

what happens at anode in electrolysis of aqueous solutions?

Answer 19

• oxygen gas usually produced from aqueous solutions
• but if solution contains halide ions, halogen will be produced

Question 20

what happens if solutions contains halide ions?

Answer 20

halogen will be produced