Energetics

Question 1

What is a chemical reaction called when heat energy is taken in?

Answer 1

Endothermic.

Question 2

What are some examples of exothermic changes?

Answer 2

• The reactions of metals with acids.
• Neutralisation reactions.
• Adding water to calcium oxide.

Question 3

What does ΔH represent?

Answer 3

Molar enthalpy change.

Question 4

Is ΔH in exothermic reactions positive or negative?

Answer 4

Negative.

Question 5

Is ΔH in endothermic reactions positive or negative?

Answer 5

Positive.

Question 6

Exothermic reactions…

Answer 6

Give energy out to the surroundings - products have less energy than reactants.

Question 7

Endothermic reactions…

Answer 7

Take energy in from the surroundings - products have more energy than the reactants.

Question 8

Breaking of bonds is…

Answer 8

Endothermic - requires energy.

Question 9

Making of bonds is…

Answer 9

Exothermic - releases energy.

Question 10

What is a chemical reaction called when heat energy is given out?

Answer 10

Exothermic.