C7.1 / C7.2/ C7.3 - Exothermic And Endothermic Reactions

Question 1

Define what an exothermic reaction is.

Answer 1

A reaction which transfers energy from the reacting chemicals to their surroundings. This in turn causes a rise in temperature.

Question 2

Define what an endothermic reaction is.

Answer 2

A reaction which transfers energy from the surroundings of the reacting chemicals causing a fall in temperature.

Question 3

Experiemnt on investigating temperature changes

Answer 3

Polystyrene cup and thermometer and mix reactants in the cup. To investigate temperature change record initial temp of soloution and that minimum or maximum temperature of the soloution. Saftey : wear eye protection

Question 4

Examples of exothermic reactions

Answer 4

Neutralisation, oxidation, combustion, respiration

Question 5

Examples of an endothermic reaction

Answer 5

Thermal decomposition, photosynthesis, reaction between citric acid and sodium hydrogen carbonate

Question 6

Uses of exothermic changes

Answer 6

Chemical hand warmers and self heating cans

Question 7

Uses of endothermic changes

Answer 7

Chemical cold packs and chilling drinks in cans