Exothermic & Endothermic Reactions

What is an exothermic reaction?

A reaction that transfers energy to the surroundings

What is an endothermic reaction?

A reaction that takes in energy from the surroundings

What is a reaction (or enthalpy) profile diagram?

A diagram that shows the energy change during a chemical reaction

What is the green box?

Reactants

What is the red box?

Activation energy

What is the grey box?

Products

Give 3 examples of exothermic reactions

1. Combustion

2. Neutralisation

3. Oxidation

Give 2 examples of endothermic reactions

1. Citric acid + sodium hydrogen carbonate

2. Thermal decomposition

Does the graph show an exothermic or an endothermic reaction? Why?

Exothermic as the energy of products is lower than reactants so energy has been lost to surroundings

Does the graph show an exothermic or endothermic reaction? Why?

Endothermic as the energy of products is higher than reactants so energy has been gained from surroundings

Do hand warmers and self heating cans use exothermic or endothermic chemical reactions?

Exothermic as they increase the temperature of their surroundings

Do sport injury cold packs use exothermic or endothermic chemical reactions?

Endothermic as they decrease the temperature of their surroundings