1) A student constructs the follwoing galvanic cell.

However, no reaction is observed.
This is most likely because
A. the difference between the E° values is too small for a reaction to occur.
B. hydrogen peroxide will oxidise water in preference to itself.
C. the student did not construct standard half-cells.
D. the rate of the reaction is extremely slow.

Solution

2) Four standard galvanic cells are set up as indicated below.

a) Which cell would be expected to develop the largest potential difference?
A. I
B. II
C. III
D. IV

Solution

b) The reaction occurring at the cathode as cell IV is discharged is
A. Fe²⁺(aq) => Fe³⁺aq) + e–
B. Fe³⁺(aq) + e– => Fe²⁺(aq)
C. Co(s) => Co²⁺aq) + 2e–
D. Co²⁺(aq) + 2e– => Co(s)

Solution

3) The main reason an aqueous solution of potassium nitrate is used in salt bridges is

Solution

4) The lead acid battery used in cars consists of secondary galvanic cells.
The following equations relate to the lead acid battery.

When an external power source is used to recharge a flat lead acid battery
A. the concentration of sulfuric acid decreases.
B. PbSO₄ is both oxidised and reduced.
C. the mass of metallic lead decreases.
D. PbO₂ is oxidised to Pb.

Solution

5) A student prepares 1.0 M aqueous solutions of AgNO₃, Fe(NO₃)₂ and KNO₃.
Equal volumes of each solution are placed in separate beakers, identical platinum electrodes are placed in each beaker and each solution undergoes electrolysis with the same current applied for 5.0 minutes under SLC. Each cathode is then dried and weighed to determine mass change.
Assume that the concentrations of the solutions have decreased only slightly.
In order of increasing mass, the metals deposited on the three cathodes are likely to be
A. potassium, silver, iron.
B. silver, iron, potassium.
C. iron, potassium, silver.
D. potassium, iron, silver.

Solution