Chemical Equilibrium is where the concentrations of products and reactions remain constant over time.
In reversible reaction, where products can re-react to form the reactants, it is said to be in dynamic equilibrium when both forward and backward reactions are happening at equal rates so the concentrations of products and reactants remain constant.
Le Chatelier’s Principle:
The principle states that ‘When a change is applied to a system in dynamic equilibrium, the system reacts in such a way as to oppose the effect of the change’. This means that if the system is altered then the system will try to counteract the change and establish a new equilibrium position.
The Equilibrium Constant (Kc )
The Equilibrium can be used to determine the concentration of a product or reactant at dynamic equilibrium, it can also tell us which side the reaction is biased to.
aA + bB ⇌ cC + dD
can vary depending on the temperature as some reactions are endothermic and exothermic, increasing the temperature will favor the endothermic reaction and decreasing it will favor the exothermic reaction. If any other factors are changed such as concentration, surface area or the catalyst then this will not affect the but it will affect the rate of reaction.
The Equilibrium Constant (Kp )
The Kp can be used to determine the concentration of different gaseous reactants or products at different pressures. In a gaseous system where the reaction that takes place is variable both the temperature and the pressure determine where the equilibrium position will lie. Higher pressure favors the side with less moles as less moles take up less space, lower pressures favour the side with more molecules.