1. Exothermic reactions
'exo' means out. If a chemical reaction gives out heat it is called 'exothermic'
e.g : burning of coal
reaction between sodium hydroxide and hydrochloric acid
2. Endothermic reactions
'Endo' means taking in heat. when energy or heat is absorbed from surrounding due to a chemical reaction it will cool the container.
e.g: dissolving ammonium chloride in water
photosynthesis
Chemical reactions happen when bonds between the reactants are broken and new bonds are made to form products. breaking the bonds requires energy. Which means
Breaking bonds is Endothermic
Making bonds releases energy. which means
Making bonds is exothermic
for any chemical reaction the energy change means the difference between the energy needed to break the bonds and energy given by making the bonds. which is also referred by the term
Enthalpy change
