C7 Flashcards
which would have a larger potential difference:
a cell containing magnesium and copper
or
a cell containing zinc and tin
magnesium and copper- because there is a greater difference in reactivity
making bonds is:
exothermic
breaking bonds is:
endothermic
what is an electrolyte?
A solution that can conduct electricity
Why do cells only produce electricity for a set time?
Eventually the chemicals will be used up and the reaction will stop
Greater difference in reactivity between the electrodes =
greater potential difference
How comes some batteries are rechargeable?
The chemical reactions can be reversed
Fuel cells: negative electrode =
2H2 –> 4H+ + 4e-
Fuel cells: positive electrode =
O2 + 4H+ + 4e- —> 2H2O
Fuel cells: overall equation
2H2 +O2 —> 2H2O
compare hydrogen fuel cells and rechargeable batteries in terms of working/ energy being provided
HFC- will provide electricity as long as hydrogen is provided
RB- will run out and need to be recharged
compare hydrogen fuel cells and rechargeable batteries in terms of: how long they work
HFC- doesn’t become any less efficient
RB- store less electricity the more they’re charged so will need replacing
compare hydrogen fuel cells and rechargeable batteries in terms of: products
HFC - produces drinkable water
compare hydrogen fuel cells and rechargeable batteries in terms of: safety
HFC - Hydrogen is highly flammable and explosive
RB - no dangerous fuels, though can catch fire if manufactured incorrectly
compare hydrogen fuel cells and rechargeable batteries in terms of: potential difference
HFC - low p.d produced so several needed
RB- produces a greater pd
