Chemical Change: Dynamic Equilibrium

Dynamic equilibrium is a state of balance achieved within a closed system when the rate of forward reaction equals the rate of backward reaction.
The term ‘closed system’ means a system where neither the reactants nor the products can escape; hence there is no loss or gain.
Dynamic equilibrium does not mean that the reactions have stopped, in fact, they are ongoing but the concentration of the substances remains constant.
Le Chatelier’s Principle provides a way to predict the effect of changing conditions on a system in dynamic equilibrium.
The principle states that if a change is made to the conditions of a reaction at dynamic equilibrium, the position of equilibrium will move to counteract that change.
Factors that can change the position of equilibrium include temperature, pressure, and concentration of reactants or products.
If the concentration of a substance is increased, the equilibrium will shift to use up the extra, if it is decreased, the equilibrium will shift to produce more.
If the pressure is increased, the equilibrium will shift towards the side with fewer gas molecules per volume, and if it is decreased, it will shift towards the side with more.
For systems that involve gases, if the volume of the system is changed, it will have an effect similar to a pressure change.
During a temperature change, if the system is heated, the equilibrium will shift in the endothermic (heat absorbing) direction to cool down the system, and if it is cooled, it will shift in the exothermic (heat releasing) direction to warm up the system.
Catalysts can speed up the rate of both the forward and backward reactions, but they do not affect the position of equilibrium.
The forward and backward reaction rates in a system at dynamic equilibrium can also be graphically represented through the concentration-time graph.
The Kc value is a constant which represents the ratio of product concentration to reactant concentration at equilibrium and can be used to calculate the equilibrium concentrations of reactants and products.
It’s necessary to understand the concepts of dynamic equilibrium and its factors to comprehend rate equations, predict the effect of changing conditions, and solve related problems in predicting reaction yields.