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Exothermic and Endothermic Reactions - Coggle Diagram
Exothermic and Endothermic Reactions
Exothermic Reactions
An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases - it gets hotter.
Common Exothermic Reactions
Combustion
Oxidation
Neutralisation
In an exothermic reaction, the energy released from forming new bonds is greater that the energy needed to break existing bonds.
Energy is conserved in chemical reactions. The amount of energy in the Universe at the end of a chemical reaction is the same as before the reaction takes place.
Endothermic Reactions
An endothermic reaction is one that takes energy from the surroundings so the temperature in the surroundings decreases - it gets colder.
In an endothermi reaction, the energy needed to break the existing bonds is greater than the energy released from forming new bonds.
Activation energy
Chemical reactions can only occur when reacting particles collide ith each other with sufficient enery.
The minimum amount of energy that particles must have to react is called activation energy.
You have given a reaction its activation energy when you have used a lit splint to light a Bunsen Burner. Without the activation energy from the lit splint, the methane gas and oxygen in the air will not combust and release the heat energy.
Reaction Profile
A reaction profile shows the activation energy of the reaction which is shown by a curved line.
Bond Energies
During a chemical reaction: energy must be supplied to break bonds in the reactants, energy is released to form bonds in the products.
Overall energy change = energy needed to break the bonds - energy released as bonds are made
If the overall is negative it is exo if it is positive it is endo.
