Energy Changes: Exothermic and Endothermic Reactions.

Question 1

What is an exothermic reaction?

Answer 1

• Transfer energy from the reacting molecules to the surroundings.
• Temperature of the surroundings increases.
• EXAMPLES:
• Combustion, Oxiditation and neutralisation.

Question 2

What does the energy profile for an exothermic reaction look like?

Answer 2

• Products have less energy than the reactants.
• Energy has been transferred from the reacting molcules to the surroundings.
• ## The difference between the energy of the reactants and the energy of the products tells us the energy that has been released into the surroundings.

Question 3

Where can we find exothermic reactions?

Answer 3

• Hand-warmers:
• ## Self heating cans.

Question 4

What is an endothermic reaction?

Answer 4

• Takes in energy from the surroundings.
• temperature of the surroundings decreases.
• Example: Thermal decomposition.

Question 5

What does the energy profile for endothermic reactions look like?

Answer 5

• Products have more energy than the reactants.
• Energy has been taken in from the surroundings.
• The difference in energy between the reactants and the products tells us the amount of energy that has been taken in by the reaction.

Question 6

In the energy profiles what does the peak show?

Answer 6

• Acitivation energy.

- From the reactants to the peak of the curve.