Electrolysis

Question 1

What is electrolysis?

Answer 1

The splitting up of a compound using electricity

Question 2

What is the half equation for the electrolysis of lead

Answer 2

Pb–>Pb 2+ +2e-

Question 3

What is the equation for the formation pf bromine

Answer 3

2Br+2e- –> 2Br-

Question 4

What state mus the compound be in for electrolysis

Answer 4

Liquid (aqueous solution) or molten

Question 5

What is the cathode

Answer 5

The negative terminal, full of electrons

Question 6

What is the anode

Answer 6

Positive terminal, lack of electrons

Question 7

Why are the elements in the compounds attracted to the cathode or anode

Answer 7

Because opposites attract

Question 8

What is oxidation

Answer 8

The loss of electrons

Question 9

What is reduction

Answer 9

Gain of electrons

Question 10

Where does oxidation occur

Answer 10

At the anode

Question 11

Where does reduction occur

Answer 11

At the cathode

Question 12

What is an aqueous solution

Answer 12

Something dissolved in water

Question 13

What happens to water molecules during electrolysis

Answer 13

They also ionise, forming hydrogen ions (+) and hydroxide ions (-)

Question 14

What is a reversible reaction

Answer 14

A reaction that can happen both ways

Question 15

What happens at the anode during the electrolysis of NaCl dissolved in water

Answer 15

The chloride ions lose one electron each at the positive anode, pair up and become chloride gas (oxidation). The hydroxide ions get left behind in the solution

Question 16

What is the half equation for chlorine at the anode

Answer 16

2Cl+ –> Cl(2) + 2e-

Question 17

What happens to sodium at the cathode

Answer 17

The sodium is more reactive than the hydrogen, meaning that hydrogen gas is released (H2). This means that sodium ions are left behind in the solution

Question 18

What is the half equation for what happens at the cathode during the electrolysis of NaCl

Answer 18

2H+ + 2e- –> H2

Question 19

What are the rules of electrolysis for positive ions

Answer 19

If the metal is less reactive then hydrogen, then it forms at the cathode, but if it is more reactive than hydrogen, then hydrogen gas is released at the cathode

Question 20

What are the rules pf electrolysis for negative ions

Answer 20

If halide (group 7) ions are present, they will be released at the anode. Next, is hydroxide ions,releasing oxygen at the anode. Half equation ( 4OH- –> 2H2O + O2 + 4e-). Any larger ions come next

Question 21

What is the overall equation for the electrolysis of aluminium oxide

Answer 21

2Al2 O3 (l) –> 4Al (l)+ 3O2 (g)

Question 22

Why are electrodes made from carbon graphite

Answer 22

Because they are solid, unreactive and good conductors

Question 23

What is the half equation for the aluminium in aluminium oxide

Answer 23

Al3+ (l) + 3e- –>Al (l) (reduction)

Question 24

What is the half equation for the oxygen in the aluminium oxide

Answer 24

2O2- (l) –> O2 (g) + 4e- (oxidation)

Question 25

What is phytomining

Answer 25

The extraction of copper using plants

Question 26

What is bioleaching

Answer 26

The extraction of copper using bacteria

Question 27

What is the word and symbol equation for the displacement reaction of adding scrap iron to the copper

Answer 27

Iron+ copper (II) sulfate --> iron (III) sulfate + copper | Fe (s) + Cu2+ (aq) --> Fe 2+ (aq) + Cu (s)

Question 28

Where are the pure and impure copper sheers placed during the reaction

Answer 28

The pure copper sheet is placed at the cathode, with the impure copper sheet placed at the anode

Question 29

What reaction happens at the cathode

Answer 29

Cu2+ (aq) + 2e- --> Cu (s)

Question 30

Why does the cathode strip get larger

Answer 30

Because solid copper is deposited there

Question 31

What reaction happens at the anode

Answer 31

Cu (s) --> Cu2+ (aq) + 2e-

Question 32

Why is there sludge at the anode

Answer 32

Because as the copper from the anode replaces the copper in the solution, other valuable materials below copper in the reactivity series are deposited at the bottom of the container