CC10 Electrolysis

Question 1

Magnesium carbonate is insoluble. What do you need to do before it will conduct electricity?

Answer 1

Melt it

Question 2

Sodium fluoride is soluble. Explain what the easiest way for it to conduct electricity is

Answer 2

Dissolve it in water because this does not require high temperatures

Question 3

Which ions are in NaCl

Answer 3

Na⁺ and Cl⁻

Question 4

Which ions are in CuCl₂

Answer 4

Cu²⁺ and two Cl⁻

Question 5

Which ions are in Na₂SO₄

Answer 5

2 ions of Na⁺ and one SO₄²⁻

Question 6

Is this process oxidation or reduction? Al → Al³⁺ + 3e⁻

Answer 6

Oxidation

Question 7

Is this process oxidation or reduction? Na⁺ + e⁻ → Na

Answer 7

Reduction

Question 8

Is this process oxidation or reduction? F₂ + 2e⁻ → 2F⁻

Answer 8

Reduction

Question 9

Is this process oxidation or reduction? Fe²⁺ → Fe³⁺ + e⁻

Answer 9

Oxidation

Question 10

In this reaction, what has been oxidised and what has been reduced? Mg²⁺ + 2Na → 2Na⁺ + Mg

Answer 10

Na has been oxidised, Mg²⁺ has been reduced

Question 11

In this reaction, what has been oxidised and what has been reduced? 2Al + 3Ca²⁺ → 2Al³⁺ + 3Ca

Answer 11

Al has been oxidised, Ca²⁺ has been reduced

Question 12

In this reaction, what has been oxidised and what has been reduced? K + Na⁺ → K⁺ + Na

Answer 12

K has been oxidized, Na⁺ has been reduced

Question 13

What is electrolysis?

Answer 13

Using a dc electric current to decompose (break down) a substance

Question 14

What is an electrolyte?

Answer 14

An ionic compound in the molten state or dissolved in water

Question 15

What happens to an ionic substance when it is melted or dissolved in water?

Answer 15

The ions become free to move around

Question 16

What is the name for the positive electrode?

Answer 16

The anode

Question 17

What is the name for the negative electrode?

Answer 17

The cathode

Question 18

Do positive ions move to the anode or the cathode?

Answer 18

Cathode

Question 19

Do negative ions move to the anode or the cathode?

Answer 19

Anode

Question 20

Where does reduction occur?

Answer 20

Cathode

Question 21

Where does oxidation occur?

Answer 21

Anode

Question 22

At which electrode would Zn²+(aq) turn into Zn(s)?

Answer 22

Cathode (needs to gain electrons)

Question 23

At which electrode would Cl⁻(aq) turn into Cl₂(g)?

Answer 23

Anode (needs to lose electrons)

Question 24

Balance the equation: Al³⁺ + e⁻ → Al

Answer 24

Al³⁺ + 3e⁻ → Al

Question 25

Balance the equation: Cl⁻ → Cl₂ + e⁻

Answer 25

2Cl⁻ → Cl₂ + 2e⁻

Question 26

Balance the equation: O²⁻ → O₂ + e⁻

Answer 26

2O²⁻ → O₂ + 4e⁻

Question 27

What will be the products of the electrolysis of molten iron bromide?

Answer 27

Iron and bromine

Question 28

What will be the products of the electrolysis of molten zinc oxide?

Answer 28

Zinc and oxygen

Question 29

Define oxidation in terms of electrons

Answer 29

Oxidation is the loss of electrons

Question 30

Define reduction in terms of electrons

Answer 30

Reduction is the gain of electrons

Question 31

What will be the products of the electrolysis of sodium sulfate solution?

Answer 31

Hydrogen gas and Oxygen gas

Question 32

What will be the products of the electrolysis of acidified water?

Answer 32

Hydrogen gas and Oxygen gas

Question 33

When copper sulphate solution is electrolysed using copper electrodes. What happens to the change in mass of the electrodes if you increase the current?

Answer 33

As current increases so does the change in mass.

Question 34

When copper sulphate solution is electrolysed using copper electrodes. What happens to the mass of the electrodes?

Answer 34

The cathode mass increases. The anode mass decreases.

Question 35

Why use propanone to dry the electrodes when reweighing them after the electrolysis.

Answer 35

It evaporates drying the electrodes, no need to physically dry them.

Question 36

What will be the products of the electrolysis of copper chloride solution?

Answer 36

Copper and chlorine

Question 37

What will be the products of the electrolysis of molten lead bromide?

Answer 37

lead and bromine

Question 38

In the electrolysis of sodium chloride solution, what are the products?

Answer 38

Chlorine gas and hydrogen gas

Question 39

Why is sodium not produced in the electrolysis of sodium chloride solution?

Answer 39

It is more reactive than hydrogen so hydrogen is produced instead.

Question 40

What is produced at the anode in electrolysis of solutions?

Answer 40

Either a halogen or oxygen (when there is no halogen present)

Question 41

What is produced at the cathode in electrolysis of solutions?

Answer 41

Which ever substance is the least reactive of the cations