Chem - Energy Changes

Question 1

What is an exothermic reaction ?

Answer 1

A reaction which gives out thermal energy to the surroundings so will feel warm to the touch

Question 2

What is an endothermic reaction

Answer 2

A reaction which takes in energy from the surroundings and so will feel cool to the touch

Question 3

Explain activation energy

Answer 3

The energy needed for particles to collide with enough force to cause a reaction

Question 4

Why are endothermic reactions less common than exothermic

Answer 4

They require a larger activation energy

Question 5

What are the energy changes during a reaction

Answer 5

1. Energy must be supplied to break the bonds

2. Energy is released when new bonds are formed

Question 6

How do you calculate the overall energy change of a reaction

Answer 6

It’s the difference between the sum of the energy needed to break the bonds and the sum of the energy produced from bonds forming

Question 7

If the energy released from bonds forming is greater than the energy taken in what sort of reaction is it

Answer 7

Exothermic