Topic 5: Energy Changes

Question 1

Exothermic reaction

Answer 1

A type of reaction where the energy from the reacting chemicals is transferred to the surroundings, leading to a rise in the surrounding’s temperature

Question 2

Endothermic reaction

Answer 2

A type of reaction where the energy from the surroundings is transferred to the reacting chemicals, leading to a decrease in the surrounding’s temperature

Question 3

ENERGY TRANSFER PRACTICAL

Answer 3

-

Question 4

Uses of exothermic reactions

Answer 4

1) Hand warmers

2) Self heating cans

Question 5

Examples of endothermic reactions

Answer 5

1) Citric acid + Sodium hydrogencarbonate

2) Thermal decomposition

Question 6

Bond breaking

Answer 6

Energy must be supplied to break bonds therefore they are endothermic – the energy supplied to break bonds is greater than the energy released to form them

Question 7

Bond making

Answer 7

Energy is released when new bonds are formed therefore, they are exothermic – the energy released from to form bonds is greater than the energy used to break them

Question 8

Overall energy change

Answer 8

Energy required to break bonds - Energy required to form bonds