Question 1

Exothermic Reactions

Accepted Answer

Exothermic reactions involve the transfer of energy from the reacting chemicals to the surroundings. During a practical investigation, an exothermic reaction would show an increase in temperature as the reaction takes place. In an exothermic reaction, the reactants are at a higher energy level than the products. In an exothermic reaction, the difference in energy is released to the surroundings so the temperature of the surroundings increases. This shows in the energy profile as an overall negative energy change as energy is lost from the system.

Question 2

Endothermic Reactions

Accepted Answer

Endothermic reactions involve the transfer of energy from the surroundings to the reacting chemicals. During a practical investigation, an endothermic reaction would show a decrease in temperature as the reaction takes place. In an endothermic reaction, the reactants are at a lower energy level than the products. In an endothermic reaction, the difference in energy is absorbed from the surroundings and so the temperature of the surroundings decreases. This is shown as an increase in energy on the energy profile as the products have more energy than the reactants.

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AQA Chemistry Paper 1 Revision: Energy Changes