What is the meaning of equilibrium in Chemistry?

The meaning of equilibrium in Chemistry is simple, it means the rate of forward and backward reaction in a reversible system being equal causing the concentrations of reactants and products remaining constant.

Equilibrium in Chemistry means that the rate of forward reaction equals the rate of backward reaction meaning that the concentration of reactants and products remains constant.

Equilibrium in Chemistry indicates that the concentration of reactants and products remains constant but not same.

There are certain features of properties that characterize a chemical reaction in equilibrium.

Examples on Explanation of Meaning of Equilibrium in Chemistry

To really understand the meaning of equilibrium in Chemistry,  we need to use examples to buttresstge concept.

Consider the equilibrium state of this chemical reaction

CaCO₃ === CaO + CO₂

Equilibrium position can shift to the right ( favouring forward reaction) or to the left ( favouring backward reaction)

This depends on the conditions I.e external constraint prevalent in such cases.

However, the shift in equilibrium is only temporal and is geared towards neutralising the effect of the constraint imposed thus equilibrium is attained again with tine.

The dynamics in chemical equilibrium only deals with the fact that the equilibrium state is not permanent meaning that it is subject to change when constraints are imposed.

In fact, our understanding of equilibrium in Chemistry helps on determining maximum amounts of products formed during chemical reactions because we can then upset the equilibrium state to get a particular product in the reversible reaction.

I know I sounded vague but what I’m saying is simply that reversible chemical reactions in dynamic is altered by changes in Temperature, Pressure and concentration.

When external constraint are imposed, the equilibrium position shifts so as to annul or neutralize the constraint

There are three external constraint that when imposed on a system in equilibrium will shift either to left or right neutralizing the effect of the effect.

Le Chatelier Principle and equilibrium in Chemistry

Le Chatelier Principle states that when an external constraint such as change in Temperature, Pressure or Concentration is imposed on a system in equilibrium, the equilibrium position will shift in order to annul the effect.

Effects of external constraint on equilibrium position

External constraint on Equilibrium	Changes in equilibrium position
Effect of change in Temperature	Hint Increase in temperature favours endothermic reaction Decrease in temperature favours exothermic reaction Consider the reaction below   N2 + 3H2 ===2NH3 Change in enthalpy= -ve   What is the effect of increase and change in Temperature?   Solution Effect of increase in temperature favours backward reaction shifting the equilibrium position to the left since backward reaction is endothermic.  Effect of decrease in temperature favours forward reaction shifting the equilibrium position to the right since forward reaction is exothermic.
Effect of change in pressure	Hint Increase in pressure favours the reaction side with less volume (less number of moles) Decrease in pressure favours the reaction side with larger volume (higher number of moles) Consider the reaction below 2SO2  + O2 == 2SO3   Solution Effect of increase in pressure Increase in pressure will favour forward reaction shifting the equilibrium position to the right since it tit the side with a smaller number of moles     Effect of decrease in pressure Decrease in pressure will favour backward reaction shifting the equilibrium position to the left since it the side with higher number of moles
Effect of change in Concentration	Hint Increasee in concentration one side of the equation favours the other side of the equation Decrease in concentration one side favours the same side of the equation Consider the equation Mg + ZnCl2 ==MgCl2 + Zn What is the effect of changes in concentration? Solution   Effect of increase in amount of Magnesium   When more Magnesium particles are added, the equilibrium position will shift to the right favouring forward reaction producing more of MgCl2 and Zn.  Effect of decrease in amount of zinc When Magnesium particles are removed, the equilibrium position shifts to the left favouring backward reaction producing more of Magnesium and ZnCl2.

So in conclusion, the equilibrium in Chemistry is dynamic in nature and the reason is because an external constraints when added alter the state of the equilibrium making the equilibrium state only temporal.

However, equilibrium is attained and maintained with time since the system neutralizes or counterbalances the effect of equilibrium by adjusting via shifting the equilibrium position to the left or right.