6 Electrochemistry

Question 1

Define the term standard cell potential, . Ref: 9701/41/M/J/16

Answer 1

SCP is the EMF/ potential of a cell composed of two electrodes (OR half cells) under standard conditions (OR at 289K OR 1 moldm–3)

Question 2

Define the term standard electrode potential. Ref: 9701/41/O/N/16

Answer 2

(emf / potential /E) of an electrode OR a half-cell compared to / connected to (S)HE which can be called a “hydrogen half-cell” at concentration of 1 mol dm–3 and pressure of 1 atm (or in Pa) OR 298K

Question 3

Iron(III) ions can oxidise vanadium metal. Construct an equation for the reaction of an excess of iron(III) ions with vanadium metal. Use of the Data Booklet will be helpful. Ref: 9701/41/O/N/16

Answer 3

4Fe3+ + V + H2O → VO2+ +4Fe2+ +2H+

Question 4

The diagram shows the apparatus used to measure the standard electrode potential, Eo , of Fe3+(aq)/Fe2+(aq).

Identify what the letters A to F represent.

Ref: 9701/42/F/M/17

Answer 4

A – H2, 1 atm

B – platinum

C – 1 mol dm–3 H+ /HCl etc.

D – salt bridge /KNO3 etc.

E – platinum

F – 1 mol dm–3 Fe2+ AND 1 mol dm–3 Fe3+

Question 5

What is standard cell potential?

Answer 5

It is the potential difference between 2 half cells under the standard conditions of 1 moldm-3 and 1 atm pressure.