C7

Question 1

which would have a larger potential difference:
a cell containing magnesium and copper
or
a cell containing zinc and tin

Answer 1

magnesium and copper- because there is a greater difference in reactivity

Question 2

making bonds is:

Answer 2

exothermic

Question 3

breaking bonds is:

Answer 3

endothermic

Question 4

what is an electrolyte?

Answer 4

A solution that can conduct electricity

Question 5

Why do cells only produce electricity for a set time?

Answer 5

Eventually the chemicals will be used up and the reaction will stop

Question 6

Greater difference in reactivity between the electrodes =

Answer 6

greater potential difference

Question 7

How comes some batteries are rechargeable?

Answer 7

The chemical reactions can be reversed

Question 8

Fuel cells: negative electrode =

Answer 8

2H2 –> 4H+ + 4e-

Question 9

Fuel cells: positive electrode =

Answer 9

O2 + 4H+ + 4e- —> 2H2O

Question 10

Fuel cells: overall equation

Answer 10

2H2 +O2 —> 2H2O

Question 11

compare hydrogen fuel cells and rechargeable batteries in terms of working/ energy being provided

Answer 11

HFC- will provide electricity as long as hydrogen is provided
RB- will run out and need to be recharged

Question 12

compare hydrogen fuel cells and rechargeable batteries in terms of: how long they work

Answer 12

HFC- doesn’t become any less efficient
RB- store less electricity the more they’re charged so will need replacing

Question 13

compare hydrogen fuel cells and rechargeable batteries in terms of: products

Answer 13

HFC - produces drinkable water

Question 14

compare hydrogen fuel cells and rechargeable batteries in terms of: safety

Answer 14

HFC - Hydrogen is highly flammable and explosive
RB - no dangerous fuels, though can catch fire if manufactured incorrectly

Question 15

compare hydrogen fuel cells and rechargeable batteries in terms of: potential difference

Answer 15

HFC - low p.d produced so several needed
RB- produces a greater pd