Electrolytic processes

Question 1

What is an electrolyte?

Define aqueous?

Answer 1

An ionic compound in its molten or
aqueous state.

Aqueous - dissolved in water

Question 2

Why can an electrolyte carry charge?

Answer 2

An ionic compound in is molten or
aqueous state has mobile ions which can
carry charge.

Question 3

What is electrolysis?

Answer 3

Aprocess which uses electrical energy
(from a direct current supply) to
decompose electrolytes

Question 4

What is the cathode and anode?

Answer 4

Cathode - negative electrode

Anode - positive electrode

Question 5

Where do charged ions in the electrolyte move to

during electrolysis?

Answer 5

Cations (positive ions) move towards the
cathode (negative electrode).

Anions (negative ions) move towards the
anode (positive electrode).

Question 6

What happens at the anode during electrolysis?

Answer 6

The anions (negatively charged ions)
lose electrons to form their elements.

Question 7

What happens at the cathode during electrolysis?

Answer 7

Cations (positively charged ions) gain

electrons to form their elements.

Question 8

Name the processes that occur at each electrode

during electrolysis

Answer 8

Anode (positive) - oxidation.

Cathode (negative) - reduction

Question 9

What is formed at each electrode in electrolysis?

Answer 9

Positive electrode (Anode): Non-metal.
Negative electrode (Cathode): Metal or hydrogen.

Question 10

How can you predict whether a metal or hydrogen

will form at the negative electrode?

Answer 10

If hydrogen is above the metal in
reactivity series then the metal will form.
If the metal is more reactive than
hydrogen then hydrogen will form

Question 11

What is formed at each electrode during the

electrolysis of copper chloride solution?

Answer 11

Positive electrode: Chlorine

Negative electrode: Copper

Question 12

What is formed at each electrode during the electrolysis of sodium sulfate solution?

Answer 12

Positive electrode: Oxygen

Negative electrode: Hydrogen

Question 13

What is formed at each electrode during the

electrolysis of molten lead bromide?

Answer 13

Positive electrode: Bromine

Negative electrode: lead

Question 14

Predict what will be formed at each electrode during

the electrolysis of molten zinc chloride

Answer 14

Positive electrode: Chlorine

Negative electrode: Zinc

Question 15

What is formed at each electrode during the

electrolysis of sodium chloride solution?

Answer 15

Positive electrode: Chlorine

Negative electrode: Hydrogen

Question 16

What is formed at each electrode during the

electrolysis of water acidified with sulfuric acid?

Answer 16

Positive electrode: Oxygen

Negative electrode: Hydrogen

Question 17

What are the half equations for the reactions
occuring at the cathode and anode during the
electrolysis of copper chloride?

Answer 17

Anode: 2Cl- → Cl2 + 2e^-
Cathode: Cu^2+ + 2e- → Cu

Question 18

What does oxidation mean in terms of electrons?

Answer 18

Loss of electrons

Question 19

What does reduction mean in terms of electrons?

Answer 19

Gain of electrons

Question 20

Describe how electrolysis of copper sulfate can be

used to purify copper

Answer 20

Place 2 copper electrodes into copper sulfate solution.

The anode should be impure copper and cathode should be pure copper.

Connect to a power supply.

The copper in the impure anode is pulled towards the cathode to form pure copper.

Impurities form as sludge below the anode.

Cu2+ ions from copper sulfate remain in solution.

Question 21

Reactivity

Answer 21

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