Exothermic and Endothermic reactions.

https://www.youtube.com/watch?v=4HS6D0hTzdg&list=PL9IouNCPbCxX74bPfz0TGVVmyGYgMarWu

Whats an exothermic reaction

They transfer energy from the reacting molecules to the surroundings. This means in exothermic reactions the temperature of the surroundings increase.

Combustion is an exothermic reaction

What does an energy profile dagram do

Scientists represent the energy changes that take place in reactions by drawing an energy profile diagram

What does energy profile diagram for exothermic reaction look lke

The products have less energy than reactants, this is because energy has been transferred from reaction to the surroundings.

The difference between the energy of reactants and energy of products tells us energy that has been released to the surroundings.

Products below reactants

What are uses of exothermic reactions

Hand warmers

Self heating cans eg for food or drink.

Whats endothermic reaction

They take in energy from their surroundings. So the temperature of the surroundings decreasse.

e.g thermal decomposition

What does energy profile diagram of endothermic reaction look like

The products have more energy than the reactants, this is because energy has been taken in from the surroundings.

The difference in energy from reactants and products tells us amount of energy that has been taken in by the reaction

Products above reactants.

Whats the activation energy

When the energy in diagram rises to a peak.

The minimum amount of energy that particles must have in order to react is called the activation energy. This is because reactions only occur when particles collide w each other.

What does activation energy look like on endothermic reaction

Lots of energy needed.

What does activation energy look like on exothermic reaction

Not much needed.