23.4 Electrode Potentials

Question 1

What is a voltaic cell?

Answer 1

A cell that converts chemical energy from redox reactions to electrical energy

Question 2

What does a half-cell contain?

Answer 2

The chemical species present in a redox half-equation

Question 3

What are the 2 types of half cells?

Answer 3

Ion/ion half cell, Metal/metal ion half cell

Question 4

Describe what is in a metal/metal ion half cell

Answer 4

A metal rod dipped in solution of its aqueous metal ion

Question 5

What does the direction of electron flow in a cell depend on?

Answer 5

The relative tendency of each electrode to release electrons

Question 6

What is in an ion/ion half-cell?

Answer 6

Ions of the same element in different oxidation states, and an inert metal electrode made of platinum

Question 7

In a cell with 2 metal/metal-ion half-cells connected, which one is oxidised?

Answer 7

The more reactive metal that releases electrons more readily

Question 8

In an operating cell, which one is the negative electrode?

Answer 8

The electrode with the more reactive metal, that loses electrons and is oxidised

Question 9

In an operating cell, which one is the positive electrode?

Answer 9

The electrode with the less reactive metal, that gains electrons and is reduced.

Question 10

What is standard electrode potential?

Answer 10

The relative tendency to be reduced and gain electrons. E⦵ /
The e.m.f of a half-cell connected to a standard hydrogen half-cell under standard conditions

Question 11

What is standard electrode potential relative to?

Answer 11

A standard hydrogen half-cell/electrode

Question 12

What is the standard electrode potential of a standard hydrogen half-cell?

Answer 12

0 volts

Question 13

How do you measure the standard electrode potential of a half-cell? (Simple answer)

Answer 13

Connect the half-cell to a standard hydrogen electrode

Question 14

How do you connect a half-cell to a standard hydrogen electrode?

Answer 14

• Use a wire to allow a controlled flow of electrons
• Use a salt bridge to allow ions to flow

Question 15

What is the function of a salt bridge?

Answer 15

Allows ions to flow.

Question 16

What is a salt bridge typically made of?

Answer 16

A concentrated solution of an electrolyte that does not react with either solution

Question 17

What is the function of the wire connecting 2 electrodes?

Answer 17

To allow a controlled flow of electrons

Question 18

The more negative the E⦵ value…

Answer 18

The greater the tendency to lose electrons and undergo oxidation

Question 19

The more positive the E⦵ value…

Answer 19

The greater the tendency to gain electrons and undergo reduction

Question 20

How do you calculate E⦵cell?

Answer 20

E⦵(positive electrode) - E⦵(negative electrode)

Question 21

Do metals tend to have positive or negative E⦵ values?

Answer 21

Negative

Question 22

What does the concentration of a metal ion in a metal/metal ion half cell have to be?

Answer 22

1 mol/dm^3

Question 23

What does the concentration of the ions in an ion/ion half-cell have to be?

Answer 23

Equal to eachother

Question 24

For a half-cell containing gases, what does the pressure of the gas, and concentration of ions have to be?

Answer 24

100kPa, and 1 mol/dm^3

Question 25

For a half-cell containing gases, what does the electrode have to be?

Answer 25

Inert, typically platinum

Question 26

For all half-cells, what must the temperature be?

Answer 26

298K

Question 27

In which direction do electrons flow along the wire?

Answer 27

From the more negative half-cell to the less negative half-cell