First of all you need a chemical system ie a system in which there are at least two reactants to start with. Then there needs to be a reaction between the reactants so that products are being created. Finally it needs to be determined at what point there are no more products being created, and that then should represent equilibrium.
Chemical system is at equilibrium if both reactants and products are present in concentrations which have no further tendency to change with time. To determine whether or not a chemical system is at equilibrium the following things need to be taken into consideration: 1. If the system is open, the chemical system is 100% not in equilibrium. (Equilibrium may only be obtained in a closed system). 2. If the forward and reverse reactions are happening at equal rates, then the system is at equilibrium. 3. If the products and reactants are present in equal concentrations, then the system is at equilibrium.
