C6.4 - Electrolysis of aqueous solutions

Question 1

Brine

Answer 1

Brine is a concentrated sodium chloride solution

Question 2

What is the electrolysis of brine in relation to industry?

Answer 2

The electrolysis of brine is a very important large-scale industrial process

Question 3

When brine is electrolysed, what 3 useful products do you get that are used to make other chemicals?

Answer 3

When brine is electrolysed, the 3 useful products you get that are used to make other chemicals are:

1. Chlorine gas
2. Hydrogen gas
3. Sodium hydroxide solution

Question 4

When brine is electrolysed, why is sodium hydroxide left in the solution?

Answer 4

When brine is electrolysed, sodium hydroxide is left in the solution, because there are 4 different ions in brine - Na+, Cl-, H+ and OH-, all aqueous

Question 5

Whenever hydrogen is produced at the cathode during electrolysis, what do the hydrogen atoms formed do?

Answer 5

Whenever hydrogen is produced at the cathode during electrolysis, the hydrogen atoms formed:

1. Bond together in pairs
2. Are given off as hydrogen gas, H2

Question 6

In the electrolysis of brine, you can test the solution around the cathode with what?

Answer 6

In the electrolysis of brine, you can test the solution around the cathode with an acid/base indicator

Question 7

In the electrolysis of brine, if you test the solution around the cathode with an acid/base indicator, what will it show?

Answer 7

In the electrolysis of brine, if you test the solution around the cathode with an acid/base indicator, it will show that the solution is alkaline

Question 8

What should be considered in relation to brine?

Answer 8

The environmental impacts of the electrolysis of brine on a large scale should be considered

Question 9

What does the process of the electrolysis of brine use?

Answer 9

The process of the electrolysis of brine uses a lot of electricity that is mainly produced by the burning of fossil fuels

Question 10

What must be in contact with the solution of brine during the actual process of electrolysis?

Answer 10

A metal must be in contact with the solution of brine during the actual process of electrolysis

Question 11

A metal must be in contact with the solution of brine during the actual process of electrolysis.
What is a metal most commonly used?

Answer 11

A metal most commonly used is mercury

Question 12

Ions present in a solution of potassium bromide

Answer 12

The ions present in a solution of potassium bromide are:

1. K+
2. Br-
3. H+
4. OH-

Question 13

The product at the cathode in the electrolysis of a solution of potassium bromide

Answer 13

The product at the cathode in the electrolysis of a solution of potassium bromide is hydrogen gas

Question 14

The product at the anode in the electrolysis of a solution of potassium bromide

Answer 14

The product at the anode in the electrolysis of a solution of potassium bromide is bromine

Question 15

Observations you can see at the anode in the electrolysis of a solution of potassium bromide

Answer 15

The observations you can see at the anode in the electrolysis of a solution of potassium bromide are:

1. Bubbles
2. A reddish-brown solution of bromine

Question 16

Ions present in a solution of sodium sulfate

Answer 16

The ions present in a solution of sodium sulfate are:

1. Na+
2. S2-
3. H+
4. OH-

Question 17

The product at the cathode in the electrolysis of a solution of sodium sulfate

Answer 17

The product at the cathode in the electrolysis of a solution of sodium sulfate is hydrogen gas

Question 18

The product at the anode in the electrolysis of a solution of sodium sulfate

Answer 18

The product at the anode in the electrolysis of a solution of sodium sulfate is oxygen gas

Question 19

Ions present in a solution of copper(II) chloride

Answer 19

The ions present in a solution of copper(II) chloride are:

1. Cu2+
2. Cl-
3. H+
4. OH-

Question 20

The product at the cathode in the electrolysis of a solution of copper(II) chloride

Answer 20

The product at the cathode in the electrolysis of a solution of copper(II) chloride is copper

Question 21

The product at the anode in the electrolysis of a solution of copper(II) chloride

Answer 21

The product at the anode in the electrolysis of a solution of copper(II) chloride is chlorine gas

Question 22

Observations you can see at the anode in the electrolysis of a solution of copper(II) chloride

Answer 22

The observations you can see at the anode in the electrolysis of a solution of copper(II) chloride are that damp litmus paper is bleached, turning white

Question 23

When brine is electrolysed, what is produced at the anode?

Answer 23

When brine is electrolysed, chlorine gas is produced at the anode

Question 24

When brine is electrolysed, chlorine gas is produced at the anode.
When brine is electrolysed, what is produced at the cathode?

Answer 24

When brine is electrolysed, hydrogen gas is produced at the cathode

Question 25

When brine is electrolysed, chlorine gas is produced at the anode. When brine is electrolysed, hydrogen gas is produced at the cathode. When brine is electrolysed, what is the remaining solution?

Answer 25

When brine is electrolysed, the remaining solution is sodium hydroxide solution

Question 26

When brine is electrolysed, why is hydrogen gas produced at the cathode?

Answer 26

When brine is electrolysed, hydrogen gas is produced at the cathode, because sodium is more reactive than hydrogen

Question 27

Aluminium is extracted by electrolysis. | Why can aluminium not be extracted by heating aluminium oxide with carbon?

Answer 27

Aluminium can not be extracted by heating aluminium oxide with carbon, because aluminium is more reactive than carbon in the reactivity series

Question 28

In the electrolysis of aluminium oxide, what is formed at the negative electrode?

Answer 28

In the electrolysis of aluminium oxide, molten aluminium is formed at the negative electrode

Question 29

What observations would you see if hydrogen gas or oxygen gas is produced?

Answer 29

The observations you would see if hydrogen gas or oxygen gas is produced are: 1. Bubbles 2. Fizzing

Question 30

If a metal is too reactive to be reduced with carbon or reacts with carbon, then electrolysis can be used to extract it. What is extracting metals via this method?

Answer 30

Extracting metals via the method of electrolysis is very expensive

Question 31

At the negative electrode (cathode) when is hydrogen produced?

Answer 31

At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen

Question 32

At the positive electrode (anode), what is produced unless the solution contains halide ions?

Answer 32

At the positive electrode (anode), oxygen gas is produced, unless the solution contains halide ions

Question 33

At the positive electrode (anode), oxygen gas is produced, unless the solution contains halide ions. What would happen if halide ions are present?

Answer 33

If halide ions are present, the halide would be formed

Question 34

Industrial uses of electrolysis

Answer 34

Industrial uses of electrolysis are: 1. To manufacture chlorine, sodium hydroxide, hydrogen and sodium 2. Electroplating of steel

Question 35

What is bleach made from?

Answer 35

Bleach is made from: 1. Chlorine 2. Sodium hydroxide obtained from the electrolysis of brine

Question 36

What is the chlorine made when you electrolyse brine in industry used to do?

Answer 36

The chlorine made when you electrolyse brine in industry is used to kill bacteria in: 1. Drinking water 2. In some swimming pools

Question 37

When brine is electrolysed, the 3 useful products you get that are used to make other chemicals are chlorine gas, hydrogen gas and sodium hydroxide solution. Chlorine gas is produced at the what?

Answer 37

Chlorine gas is produced at the anode

Question 38

When brine is electrolysed, the 3 useful products you get that are used to make other chemicals are chlorine gas, hydrogen gas and sodium hydroxide solution. Hydrogen gas is produced at the what?

Answer 38

Hydrogen gas is produced at the cathode

Question 39

When brine is electrolysed, sodium hydroxide is left in the solution, because there are 4 different ions in brine - Na+, Cl-, H+ and OH-, all aqueous. The Cl- and H+ ions are removed during electrolysis as they move to what?

Answer 39

The Cl- and H+ ions are removed during electrolysis as they move to the: 1. Anode 2. Cathode

Question 40

When brine is electrolysed, sodium hydroxide is left in the solution, because there are 4 different ions in brine - Na+, Cl-, H+ and OH-, all aqueous. The Cl- and H+ ions are removed during electrolysis as they move to the anode and cathode, because what?

Answer 40

The Cl- and H+ ions are removed during electrolysis as they move to the anode and cathode, because: 1. Halide ions are first in the order of discharge at the anode 2. Sodium is more reactive than hydrogen

Question 41

When brine is electrolysed, sodium hydroxide is left in the solution, because there are 4 different ions in brine - Na+, Cl-, H+ and OH-, all aqueous. The Cl- and H+ ions are removed during electrolysis as they move to the anode and cathode, because halide ions are first in the order of discharge at the anode and sodium is more reactive than hydrogen, so this leaves a solution of what?

Answer 41

The Cl- and H+ ions are removed during electrolysis as they move to the anode and cathode, because: 1. Halide ions are first in the order of discharge at the anode 2. Sodium is more reactive than hydrogen ,so this leaves a solution of sodium hydroxide, NaOH

Question 42

In the electrolysis of brine, if you test the solution around the cathode with an acid/base indicator, it will show that the solution is alkaline, because what?

Answer 42

In the electrolysis of brine, if you test the solution around the cathode with an acid/base indicator, it will show that the solution is alkaline, because sodium hydroxide solution is alkaline

Question 43

A metal must be in contact with the solution of brine during the actual process of electrolysis. A metal most commonly used is mercury, which is what?

Answer 43

A metal most commonly used is mercury, which is toxic

Question 44

A metal must be in contact with the solution of brine during the actual process of electrolysis. A metal most commonly used is mercury, which is toxic and some mercury does what?

Answer 44

A metal most commonly used is mercury, which is toxic and some mercury escapes into the: 1. Solution 2. Environment

Question 45

The observations you can see at the anode in the electrolysis of a solution of copper(II) chloride are that damp litmus paper is bleached, turning white, but if you use blue litmus paper, it may turn what for a moment first?

Answer 45

The observations you can see at the anode in the electrolysis of a solution of copper(II) chloride are that damp litmus paper is bleached, turning white, but if you use blue litmus paper, it may turn red for a moment first

Question 46

The observations you can see at the anode in the electrolysis of a solution of copper(II) chloride are that damp litmus paper is bleached, turning white, but if you use blue litmus paper, it may turn red for a moment first, because what?

Answer 46

The observations you can see at the anode in the electrolysis of a solution of copper(II) chloride are that damp litmus paper is bleached, turning white, but if you use blue litmus paper, it may turn red for a moment first, because a solution of chlorine is acidic

Question 47

Aluminium can not be extracted by heating aluminium oxide with carbon, because aluminium is more reactive than carbon in the reactivity series, so what has to be used?

Answer 47

Aluminium can not be extracted by heating aluminium oxide with carbon, because aluminium is more reactive than carbon in the reactivity series, so electrolysis has to be used

Question 48

In the electrolysis of aluminium oxide, molten aluminium is formed at the negative electrode. The liquid aluminium does what?

Answer 48

The liquid aluminium runs to the bottom of the cell, where it is tapped off

Question 49

If a metal is too reactive to be reduced with carbon or reacts with carbon, then electrolysis can be used to extract it. Extracting metals via the method of electrolysis is very expensive, because what?

Answer 49

Extracting metals via the method of electrolysis is very expensive, because lots of energy is required to: 1. Melt the ore 2. Produce the required current