Redox a2

Question 1

What do redox reactions do?

Answer 1

Transfer electrons from 1 species to another

Question 2

Standard electrode potential

Answer 2

e.m.f- electromotive force of a half cell compared with a standard hydrogen half cell
Standard conditions- 298K, 1 mol dm3, 100 kpa

Question 3

State one important difference between a fuel cell and a modern storage cell.

Answer 3

fuel cell reacts with oxygen to give electrical energy

Question 4

Suggest one advantage of using ethanol, rather than hydrogen, in a fuel cell for vehicles.

Answer 4

ethanol is less volatile

Question 5

Cu2+(aq) + 2e– -> Cu(s) +0.34
Ag+(aq) + e– -> Ag(s) +0.80

A standard Cu2+(aq) / Cu(s) half-cell is connected to a standard Ag+(aq) / Ag(s) half-cell.
The potential of the cell is measured.
Water is then added to the Cu2+(aq) / Cu(s) half-cell. This changes the position of equilibrium in the half-cell. The cell potential increases.
Explain in terms of equilibrium why this happens

Answer 5

-(Cu2+) concentration is less than 1 mol dm3
-equilibrium shifts to left
-more electrons are released by Cu
-cell has a bigger difference in E

Question 6

State one advantage of using hydrogen as a fuel compared with conventional fuels.

Answer 6

H2O is only product

Question 7

In vehicles, hydrogen can be stored on the surface of a solid material or within a solid
material.
State one other way that hydrogen can be stored as a fuel for vehicles.

Answer 7

as a liquid and pressurised