Electrode potentials (23)

Question 1

What is a voltaic cell?

Answer 1

An electrochemical cell that converts chemical energy into electrical energy

Question 2

What is a half cell?

Answer 2

It contains the chemical species present in a redox reaction.

Question 3

What does a half cell normal consist of?

Answer 3

A metal rod dipped in a solution of its aqueous metal ion. Normally Zn and Cu. Where the metal is in contact with the solution is called the phase boundary and here you can set up an equilibrium equation. The reduction is normally the forward reaction

Question 4

What else can a half cell consist of?

Answer 4

A platinum electrode and a Fe2+ and Fe3+ solution. There is no metal to transport the electrons into or out of the half cell so the inert platinum electrode is used

Question 5

How do you know which electrode is negative and positive?

Answer 5

You look and see which electrode has a more reactive metal and this is the one that will become oxidised as it can lose its electrons easily, this is the negative electrode. The positive electrode is the metal that is reduced and isn’t as reactive.

Question 6

How do you form an electrochemical cell?

Answer 6

You connect two half cells together and you allow the electrons to flow through an external circuit which is then measured by a voltmeter.

Question 7

Standard electrode potential

Answer 7

This is the measurement of the tendency to be reduced or oxidised.

Question 8

What is the standard that is used for the standard electrode potential?

Answer 8

An inert platinum electrode which H+ solution. This has standard conditions

Question 9

What must an electrochemical cell contain?

Answer 9

A salt bridge must be connected to allow ions to flow. An example would be a strip of filter paper soaked in potassium nitrate.

Question 10

What is the name for the voltage obtained from an electrochemical cell?

Answer 10

The electron motive force

Question 11

How do you calculate the electromotive force?

Answer 11

Do the reduction electrode-oxidation electrode

right-hand electrode-left hand electrode

Question 12

How do you know if a reaction is feasible?

Answer 12

If it has a positive voltage its feasible, if it doesn’t it’s non-feasible

Question 13

What happens if your electrode potential value is more negative?

Answer 13

• It can lose more electrons so has greater reducing power and it can undergo oxidation

Question 14

What happens if your electrode potential value is more positive?

Answer 14

It can lose fewer electrons so will have a stronger oxidising power