Electrochemistry

Question 1

Redox reaction

Answer 1

A reaction involving the transfer of electrons

Question 2

Oxidation

Answer 2

The loss of electrons

Question 3

Reduction

Answer 3

The gain of electrons

Question 4

An oxidising agent

Answer 4

A substance that accepts electrons

Question 5

A reducing agent

Answer 5

A substance that donates electrons

Question 6

Anode

Answer 6

The electrode where oxidation takes place

Question 7

Cathode

Answer 7

The electrode where reduction takes place

Question 8

Electrolyte

Answer 8

A substance that can conduct electricity due to the presence of free (mobile) ions when molten or dissolved in solution

Question 9

What is a spectator ion?

Answer 9

Ions that do not take part in the electron transfer in a redox process

Question 10

Describe a galvanic cell

Answer 10

An electrochemical cell that converts the chemical energy of spontaneous redox reactions into electrical energy

Question 11

In a galvanic cell, where at which half-cell does oxidation take place?

Answer 11

Anode

Question 12

In a galvanic cell, where at which half-cell does reduction take place?

Answer 12

Cathode

Question 13

In a galvanic cell, where at which half-cell does reduction take place?

Answer 13

Cathode

Question 14

In a galvanic cell, what reaction takes place at the anode?

Answer 14

Oxidation

Question 15

In a galvanic cell, what reaction takes place at the cathode?

Answer 15

Reduction

Question 16

What are the functions of the salt bridge, in a galvanic cell?

Answer 16

• completes the circuit
• maintains electrical neutrality in the half-cells

Question 17

What is an inert electrode?

Answer 17

A electrode that does not participate in an electrochemical reaction

Question 18

Until which point can a galvanic cell deliver current?

Answer 18

The galvanic cell has the capacity to deliver current until the reaction reaches chemical equilibrium or has run to completion

Question 19

When does the voltage of a galvanic cell equal zero?

Answer 19

Once a galvanic cell reaches chemical equilibrium or has run to completion

Question 20

What is internal resistance in relation to galvanic cells?

Answer 20

Internal resistance is opposition to the flow of charge through the electrodes and electrolytes in a cell

Question 21

What is the effect of an increased surface area of the electrodes in a galvanic cell?

Answer 21

• The rate of reaction increases by lowering the internal resistance
• maximum current that the cell can deliver increases but this does not effect the emf of the cell

Question 22

What effect does a wider, shorter and/or more conductive salt bridge have in a galvanic cell?

Answer 22

Internal resistance lowers thereby increasing the maximum current that the cell can deliver but this does not affect the emf of the cell

Question 23

Describe an electrolytic cell

Answer 23

An electrochemical cell that uses electrical energy to cause non-spontaneous redox reaction to occur. Thus, electrical energy is converted into chemical energy.

Question 24

Which terminal is the anode of an electrolytic cell?

Answer 24

Positive terminal

Question 25

Which terminal is the cathode of the electrolytic cell?

Answer 25

Negative terminal

Question 26

What type of emf indicates a spontaneous redox reaction under standard conditions?

Answer 26

Positive values if the standard emf

Question 27

What type of emf indicates a non-spontaneous redox reaction under standard conditions?

Answer 27

Negative values of the standard emf

Question 28

What are two observable differences between galvanic and electrolytic cells?

Answer 28

Galvanic:
- has a salt-bridge
- occurs within two beakers

Electrolytic:
- does not have a salt-bridge
- occurs in one beaker

Question 29

What is the purpose of a catalyst in an electrolyte?

Answer 29

Improves conductivity of the electrolyte aqueous solution

Question 30

What construction change in a galvanic cell would increase the maximum current produced in the cell?

Answer 30

• increase the surface area of the electrodes
• increase the concentration of the electrolyte
• use a wider or more conductive salt-bridge