Electrode Potentials

Question 1

How can an electrochemical cell be made?

Answer 1

An electrochemical cell can be made from two different metals dipped in salt solutions of their own ions and connected by a wire (the external circuit)

Question 2

What reactions happen in an electrochemical cell?

Answer 2

There are always two reactions that happen within an electrochemical cell - one’s an oxidation and one’s a reduction - it’s a redox process

Question 3

How do electrons flow through the wire?

Answer 3

Electrons flow through the wire from the more reactive metal to the less reactive metal

Question 4

What is the cell potential (EMF)?

Answer 4

You can put a voltmeter in the external circuit to measure the voltage between the two half cells - this is the cellpotential (EMF- electromotive force)

Question 5

The reactions happening at each electrode are what?

Answer 5

Reversible - the reactions taking place at each electrode are half-equations. The half-equations are always written with the reduction reaction going in the forward direction

Question 6

How do you measure how easily a metal is oxidised?

Answer 6

How easily a metal is oxidised is measured using electrode potentials. A metal that is easy to oxidise has a very negative electrode potential. One that’s harder to oxidise has a less negative, or positive, electrode potential

Question 7

What do you measure the electrode potential of a half-cell against?

Answer 7

Standard hydrogen electrode

Question 8

Cell potential is affected by what conditions?

Answer 8

Temperature, pressure and concentration

Question 9

Define standard electrode potential

Answer 9

The standard electrode potential of a half-cell is the voltage measured under standard conditions when the half-cell is connected to a standard hydrogen electrode

Question 10

What are the standard conditions for electrode potential?

Answer 10

1. Any solutions must have a concentration of 1.00 moldm-3
2. Any temperature must be 298K
3. The pressure must be 100kPa

Question 11

What will the reading on the voltmeter be if standard conditions are maintained?

Answer 11

If standard conditions are maintained, the reading on the voltmeter when a half-cell is connected to the standard hydrogen electrode will be the standard electrode potential of that half-cell