Energy Changes Flashcards
What is an exothermic reaction?
A reaction which transfers energy to the surroundings, usually by heating. This is shown by a rise in temperature.
Give some examples of exothermic reactions
Combustion, neutralisation reactions, oxidisation reactions. Bond formation is also exothermic.
What is an endothermic reaction?
A reaction which takes in energy from the surroundings. This is shown by a fall in temperature.
Why are some batteries non-rechargeable?
Non-rechargeable batteries contain cells which use irreversible reactions. Once one of the reactants is used up, they don’t produce any more charge and you have to replace them.
What is an electrochemical cell?
A basic system made up of two different electrodes in contact with an electrolyte.
What is a fuel cell?
An electrical cell that’s supplied with a fuel and oxygen (or air) and uses energy from the reaction between them to produce electrical energy efficiently.
How are fuel cells suitable for use in vehicles?
Fuel cells don’t produce as many pollutants as other fuels. Fuel cells are cheaper than batteries. Fuel cells store more energy so they require less charging than batteries.
