Energy Changes on Reaction - Revision

Question 1

What is an exothermic reaction?

Answer 1

In an exothermic reaction, heat is given out as bonds are being made. This gives out energy.

Tip: exothermic - expelled ;)

Question 2

What is an endothermic reaction?

Answer 2

In endothermic reactions, heat is being taken in as bonds are being broken. This requires energy.

Question 3

How would you work out the calories of an object?

Answer 3

1) Measure the starting temperature of the water in the beaker
2) Burn the object underneath the beaker
3) Measure the change in temperature of the water in the beaker (the change in temperature is the calories of the object)

Question 4

What does ΔH mean?

Answer 4

ΔH is the symbol that represents the amount of energy lost or gained in a reaction

-ΔH is exothermic (as heat is being lost)

+ΔH is endothermic (as heat is being gained)

Question 5

Represent an exothermic reaction on a simple energy level diagram.

Answer 5

Exothermic: lower energy level at end

Question 6

Represent an endothermic reaction on a simple energy level diagram.

Answer 6

Endothermic: more energy at end

Question 7

What is an activation energy?

Answer 7

The activation energy is the nergy requred to start the reaction

Question 8

Why are reactions that break bonds endothermic?

Answer 8

They are endothermic beacause heat is being taken in as it is required

Question 9

Why are reactions that make bonds exothermic?

Answer 9

They are exothermic as heat is being given out