C7 Flashcards
1
Q
Exothermic meaning
A
The energy transferred from the reacting chemicals often heats up the surroundings
2
Q
Endothermic meaning
A
They take in energy from the surroundings
3
Q
Example of exothermic reaction
A
Combustion
4
Q
What is energy measured in
A
kJ / mol
5
Q
What is the activation energy
A
The energy needed to start a reaction
6
Q
What does a fuel cell oxidise
A
Oxidising hydrogen
7
Q
What is the chemical equation for hydrogen gas for a fuel in the negatively charged electrode
A
2H_2 + 4OH- (aq) —–> 4H20 (l) + 4e-
8
Q
Advantages of hydrogen fuel cells
A
- dont need to be electically charged
- no pollutants produced
- can be a range of different sizes
9
Q
Disadvantages of hydrogen fuel cells
A
- hydrogen highly flammable
- hydrogen is sometimes produced by the cell by non renewable sources
- hyrogen is difficult to store
