Topic 5: Energy Changes (Paper 1)

Question 1

What is an exothermic reaction?

Answer 1

An exothermic reaction is one that transfers energy (From the reacting molecules) to the surroundings –> temperature of the surrounding increases

Question 2

Give 4 examples of exothermic reactions.

Answer 2

• Combustion
• Many oxidation reactions
• Neutralisation
• Respiration

Question 3

What do reaction profiles show?

Answer 3

• The relative energies of reactants and products
• The activation energy needed
• The overall energy change

Question 4

What is the energy profile diagram for an exothermic reaction?
Why do the products have less enegy thant the reactants?

Answer 4

Products have less enegy than reactants (because energy has been transferred to the surroundings.

Question 5

What are 2 real life uses of exothermic reactions?

Answer 5

• Self-heating cans
• Hand warmers

Question 6

What are endothermic reactions?

Answer 6

An endothermic reaction is one that takes in energy from the surroundings –> temperature of the surroundings decreases

Question 7

Give 4 examples of endothermic reactions.

Answer 7

• Thermal decomposition
• Melting ice cubes
• Photosynthesis
• Reaction between citric acid and sodium hydrgencarbonate

Question 8

What is the energy profile diagram for an endothermic reaction?
Why do the products have more energy than the reactants?

Answer 8

The reactants will be lower thant products

Products have more energy than reactants (because energy has been taken in form the surroundings

Question 9

Give an example of a real life endothermic reaction?

Answer 9

sports injury packs