Redox

Question 1

Define the term oxidising agent in terms of electrons (1)

Answer 1

Gains electrons

Question 2

Suggest two properties of platinum that make it suitable for use as an external electrical contact in the cell (2)

Answer 2

Unreactive

Conductor

Question 3

Suggest one reason why water is not used as a solvent (1)

Answer 3

Reacts with water

Question 4

In terms of electrons, state the meaning of the term oxidising agent (1)

Answer 4

Gains electrons

Question 5

Suggest why ethanol can be considered to be a carbon-neutral fuel (2)

Answer 5

CO2 absorbed by the plants is equal

To the CO2 released when it is used as a fuel

Question 6

State one environmental advantage of a rechargeable cell compared with a non-rechargeable cel (1)

Answer 6

Won’t contribute to landfill

Question 7

Au+ (aq) + e- –> Au (s) =1.68V
O (g) + 2H+ (aq) + 2e- –> H2O (l) = 1.23V
Explain why Au+ ions are not normally found in aqueous solution. Write an equation to show how Au+ ions would react with water. (3)

Answer 7

V of Au+ > V of O2
So Au+ ions will oxidise water
2Au+ + H2O –> 2Au + 1/2O2 + 2H+

Question 8

Suggest why the recharging of a lithium cell may lead to release of carbon dioxide into the atmosphere. (1)

Answer 8

Electricity for recharging cell may come from power station burning fossil fuels

Question 9

The zinc electrode acts as a container for the cell and is protected from external damage. Suggest why a cell often leaks after being used for a long time. (1)

Answer 9

Zinc is used up/reacted/oxidised

Question 10

Deduce one essential property of a non-reactive porous separator (1)

Answer 10

Allows ions to pass through