Electrolysis

Question 1

What is electrolysis?

Answer 1

The separation of substances into their elements using electricity.

Question 2

What happens in electrolysis?

Answer 2

An electric current is passed through an electrolyte (a molten or dissolved ionic compound) causing it to decompose

Question 3

Where do the positive ions (cations) in the electrolyte move towards?

Answer 3

The cathode (negative electrode) and are reduced so they gain electrons

Question 4

Where do the negative ions (anions) in the electrolyte move towards?

Answer 4

The anode (positive electrode) and are oxidised so they lose electrons

Question 5

What is an electrolyte?

Answer 5

Ionic compounds with freely moving ions and can conduct electricity. In the molten state or dissolved in water.

Question 6

What is the acronym about the electrodes?

Answer 6

PANIC. Positive anode negative is cathode

Question 7

What is oxidation?

Answer 7

Loss of electrons

Question 8

What is reduction?

Answer 8

Gain of electrons

Question 9

What do substances have to be in electrolysis?

Answer 9

Have to be a liquid either molten or in solution this means the ions are free to move.

Question 10

What are the two types of electrodes?

Answer 10

Inert carbon (can’t react). Copper electrodes (usually used with a copper solution)

Question 11

Electrolysis core practical.

Answer 11

Measure mass of copper electrodes at start.
Carry out electrolysis.
Measure mass of copper electrodes at end.

Question 12

What is the negative electrode?

Answer 12

Cathode. Attracts positive cations.

Question 13

What is the positive electrode called?

Answer 13

Anode. Attract negative anions.

Question 14

Rules for solution at the anode for electrolysis

Answer 14

If non metal is a halide (cl- Br-) then halide is made. If non metal is sulphate then oxygen is made because OH- ions form water which decomposes oxygen + hydrogen

Question 15

Rules for solution at cathode in electrolysis

Answer 15

If metal cation is more reactive than hydrogen, metal stays in solution + hydrogen is made. If metal is less reactive than hydrogen, metal is made

Question 16

OILRIG

Answer 16

Oxidation is loss. Reduction is gain (of electrons)

Question 17

REDOX

Answer 17

A substance is being oxidised whilst the other substance is reduced

Question 18

Half equations

Answer 18

If it’s being reduced the electrons are on left hand side of equation. If it’s oxidised electrons are on right hand side of equation

Question 19

Reactivity series acronym to know of the element is more/less reactive than hydrogen

Answer 19

Please Stop Calling Me A Crazy Zebra Instead Try Learning How Copper Saves Gold

Question 20

What happens at the cathode in copper sulphate solution? (Inert electrodes)

Answer 20

Copper is less reactive than hydrogen so copper metal is produced

Question 21

What happens at the anode in copper sulphate solution? (Inert electrodes)

Answer 21

There aren’t any halide ions so oxygen + water are produced (you see bubbles of oxygen)

Question 22

What happens in electrolysis of copper sulphate solution with copper electrodes instead?

Answer 22

The mass of anode decreases and mass of cathode increases. This is because copper is transferred from anode to cathode + pure copper is made at cathode.

Question 23

How do you measure the electrodes change of mass in copper practical?

Answer 23

Weigh them before and after experiment + find difference. Make sure electrodes are dry.