5. Energy changes

Question 1

State the law of conservation of energy.

Answer 1

Energy cannot be created or destroyed, it can only transferred

Question 2

What is an exothermic reaction?

Answer 2

A reaction where energy is transferred to the surroundings.

Question 3

What happens to the temperature of the surroundings during an exothermic reaction?

Answer 3

It increases

Question 4

What is an endothermic reaction?

Answer 4

A reaction where energy is transferred from the surroundings

Question 5

What happens to the temperature of the surroundings during an endothermic reaction?

Answer 5

It decreases

Question 6

State two uses of exothermic reactions

Answer 6

Self-heating cans, hand warmers

Question 7

State two uses of endothermic reactions

Answer 7

Some cooling sports injury packs

Question 8

Is breaking bonds endothermic or exothermic?

Answer 8

Endothermic

Question 9

Is making bonds endothermic or exothermic?

Answer 9

Exothermic

Question 10

How do you work out the overall energy change of a reaction?

Answer 10

Sum of bond energies in reactants - sum of bond energies in products