Chemistry - Topic 7 Energy Changes

Question 1

Exothermic reaction

Answer 1

A reaction that transfers energy to the surroundings so the temperature of the surroundings increases

Question 2

Endothermic reaction

Answer 2

A reaction that takes in energy from the surroundings so the temperature of the surroundings decreases

Question 3

Exothermic reactions

Answer 3

• Combustion
• Many oxidisation reactions
• Neutralisation

Question 4

Endothermic reactions

Answer 4

• Thermal decomposition
• Reaction of citric acid and sodium
• Hydrogencarbonate

Question 5

Everyday examples of exothermic reactions

Answer 5

• Self-heating cans (e.g. for coffee)
• Hand warmers

Question 6

Everyday examples of endothermic reactions


Answer 6

• Sports injury packs

Question 7

Activation energy

Answer 7

Minimum amount of energy that particles must have to react

Question 8

Reaction profile

Answer 8

1. Shows the relative energies of reactants and products
2. Shows the activation energy
3. Shows the overall energy change of a reaction

Question 9

Products have _____ energy than reactants in an exothermic reaction

Answer 9

Less

Question 10

Products have _____ energy than reactants in an endothermic reaction

Answer 10

More

Question 11

Energy changes during a chemical reaction

Answer 11

1. Energy must be supplied to break bonds in the reactants
2. Energy is released when bonds in the products are formed

Question 12

Energy taken in to break bonds > energy released when bonds are formed

Answer 12

Endothermic reaction

Question 13

Energy taken in to break bonds < energy released when bonds are formed

Answer 13

Exothermic reaction