1What is an exothermic reaction?
A reaction that transfers energy to the surroundings, usually as heat. The surroundings feel warmer
2Give two examples of exothermic reactions.
Combustion and neutralisation
3What is an endothermic reaction?
A reaction that takes in energy from the surroundings: the surroundings feel cooler
42 examples of endothermic reactions
Thermal decomposition and photosynthesis
5What is activation energy?
the energy needed for a chemical reaction to happen
6What are the pros and cons of normal batteries?
Pros: last longer, cheap to purchase and no charging required
Cons: bad for the environment and expensive to produce
7What are the pros and cons of rechargable batteries?
Pros: better for the environment, one time purchase, less manufacturing
Cons: last less longer and use fossil fuels
8What is a simple cell made from?
- 2 metals (1 very reactive and 1 unreactive), an electrolyte, wires and a voltmeter
9What are the benefits and drawbacks of a hydrogen fuel cell?
Benefits: environmentally friendly, quicker at charging, travel further
Drawbacks: hard to store hydrogen, highly flammable
10Why are metals with opposing reactivities good in cells?
The more reactive metal loses electrons and is oxidised; the less reactive metal gains electrons and is reduced & a higher voltage is produced