exothermic and endothermic reactions

• exothermic reaction: a reaction that releases energy to the surroundings, can be shown by a rise in temperature
• combustion, neutralisation reactions and many oxidation reactions are exothermic
• exothermic reactions have everyday uses such as in hand warmers and self heating cans
• endothermic reaction: a reaction where energy is taken in from the surroundings, can be shown by a fall in temperature
• endothermic reactions are less common than exothermic reactions
• the reaction between citric acid and sodium hydrogencarbonate, and thermal decomposition are endothermic
• endothermic reactions have everyday uses such as in sports injury packs
• reaction profiles: diagrams to show relative energies of reactants and products in a reaction
• exothermic reaction profile: products are at a lower energy than reactants, lower activation energy
• endothermic reaction profile: products are at a higher energy than reactants, higher activation energy
• activation energy: the minimum amount of energy the reactants need to react with eachother, the greater the activation energy the more energy needed to start reaction