electrolysis

Question 1

what is electrolysis?

Answer 1

the breaking down of a substance using electric current

Question 2

what do you call the compound broken down?

Answer 2

the electrolyte

Question 3

what are electrodes

Answer 3

conducting rods dipped into the electrolyte

Question 4

cathode

Answer 4

negative electrode

Question 5

anode

Answer 5

positive electrode

Question 6

why are the electrodes made up of an unreactive substance?

Answer 6

so that they do not react with the electrolyte / products of the reaction

Question 7

where do posituve ions move

Answer 7

cathode

Question 8

where do negative ions move

Answer 8

anode

Question 9

why do ionic substances have to be melted or dissolved in water?

Answer 9

so that their ions can move freely and carry their charge to the electrodes

Question 10

why is it difficult to predict what will form at the electrodes when in water?

Answer 10

water forms ions

Question 11

what happens to ions when they reach the electrodes

Answer 11

they either lose or gain electrons to become neutral atoms

Question 12

what happens to negative ions

Answer 12

lose electrons

Question 13

what happens to positive ions

Answer 13

gain electrons

Question 14

what is oxidation?

Answer 14

losing electrons

Question 15

what is reduction?

Answer 15

gaining electrons

Question 16

what is the rule for working out what will happen in electrolysis in water?

Answer 16

if two elements can be produced at an electrode, the LESS REACTIVE element will usually be formed

Question 17

in water:

what happens at the anode

Answer 17

hydroxide ions often discharged

give off oxygen gas

Question 18

in water:

what happens at the anode if the solution has a high concentration of a halide?

Answer 18

the halide ion is discharged and the halogen is formed

Question 19

in water:

at the cathode

Answer 19

positive metal and hydrogen ions attract.

Question 20

what is the purpose of electrolysis?

Answer 20

to break down compounds into their elements

Question 21

electrolysis is used for ores _____ than carbon on the reactivity series, a ______ is used for ores lower on the reactivity series

Answer 21

higher

blast furnace

Question 22

electrolysis of Al: cathode (equation+info)

Answer 22

Al3+ + C —> Al

• cathode is at the bottom
• collected here

Question 23

electrolysis of Al: anode (equation+info)

Answer 23

20^2- — e- —> O2

at the top.
carbon electrode, eventually lost as CO2