Chapter 7 Electrolysis

Question 1

How does electricity travel

Answer 1

Negative to positive

Question 2

What is a conductor

Answer 2

a substance that allows electricity to pass through

Question 3

What is an insulator

Answer 3

A substance that doesn’t let electricity pass through

Question 4

Why can conductors conduct

Answer 4

Because they have free electrons

Question 5

What are the solid conductors

Answer 5

Carbon (graphite)
Metals

Question 6

What is decomposition

Answer 6

The breaking down of a compound

Question 7

What is electrolysis

Answer 7

The decomposition of an ionic compound, when molten or in aqueous solution, by passing electric current.

Question 8

What is an electrolytic cell

Answer 8

The entire set up of apparatus in electrolysis

Question 9

What is the positive electrode called
What is the Negativeelectrode called

Answer 9

Anode (+)
Cathode (-)

Question 10

What is the electrolyte

Answer 10

The liquid that undergoes electrolysis

Question 11

Which electrodes are inert electrodes

Answer 11

Platinum
Carbon

Question 12

What are inert electrodes

Answer 12

Electrodes that remain unchanged, but can carry current.

Question 13

Why does decomposition occur

Answer 13

Electrons flow from negative to positive

In the liquid, ions carry the current. The ions move to the electrode of opposite charge hence current is transferred between electrodes through the solution.

Question 14

Which ion moves to which electrode and what is carried out there

Answer 14

Cations - Cathode - Reduction

Anions - Anode - Oxidation

Question 15

What are the 4 poss substances (reactivity series)that form at the cathode in the electrolysis of an aqueous solution and why?

Answer 15

Hydrogen (H)
Copper (Cu)
Silver (Ag)
Gold (Au)

They are less reactive.

Question 16

At anode what forms in a dilute solution and half equation

Answer 16

Oxygen would form

4OH- —-> 2H2O + O2 + 4e

Question 17

Half equation for water

Answer 17

H20 —> H+ + OH-

Question 18

At anode what forms in a concentrated halide solution
and the three halides that could form

Answer 18

The halogen forms
Bromine
Iodine
Chlorine

Question 19

What if there is no halide in the solution, then what forms

Answer 19

Oxygen

Question 20

What does RAC stand for

Answer 20

Reduction At Cathode

Question 21

Other uses of electrolysis

Answer 21

Metal refining
electroplating

Question 22

What is electroplating

Answer 22

Using electricity to coat one metal with another to make it look better or prevent corrosion.

Question 23

General set up for electroplating (cathode, anode, electrolyte)

Answer 23

Cathode - Object to be electroplated
Anode - Metal X
Electrolyte - A solution of soluble compound X

Question 24

in which solution do halogens get discharged

Answer 24

concentrated

Question 25

in a refining which electrode has the pure metal

Answer 25

negative electrode
cathode

Question 26

in a refining which electrode has the impure metal

Answer 26

positive electrode
anode

Question 27

which types of elements go to the cathode

Answer 27

metals and hydrogen to get reduced

Question 28

which types of elements go to the anode

Answer 28

non-metals to get oxidised

Question 29

how can we use electrolysis to determine which metal is more reactive between 2 metals e.g manganese or magnesium

Answer 29

set up a magnesium/ manganese cell
the electrode that loses mass is more reactive

Question 30

how do electrons flow

Answer 30

negative to positive

Question 31

Explain, in terms of electron transfer, why the more reactive metal is always the negative
electrode.

Answer 31

metals react by losing electrons
the more reactive metal will lose electrons more readily (making the electrode negatively charged)

Question 32

in conc aqueous what comes at anode

Answer 32

halogen

Question 33

How are electrons carried across the cell

> wires and electrodes
solution

Answer 33

wires and electrodes - electrons
solution - ions