Question

What happens when a reaction reaches Equilibrium?

Answer 1

1. Equilibrium is defined as the state of reversible chemical reaction where no net change occurs in the concentration of reactants and products.
2. It takes place in a closed system where there is no exchange of heat and energy.
3. For example - The formation of Ammonia gas.
   $$\begin{gathered} {\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\underset{150-200\mathrm{atm}}{\overset{\mathrm{Fe}/450-{500}^0\mathrm{C}}{\rightleftharpoons }}2{\mathrm{NH}}_3\left(\mathrm{g}\right) \\ \mathrm{Nitrogen}\mathrm{Hydrogen}\mathrm{Ammonia} \\ \mathrm{gas}\mathrm{gas} \end{gathered}$$
4. When any reaction attains an equilibrium stage, the rate of the forward reaction and the rate of reverse reaction becomes same or equal and their concentration become constant.
5. Thus, the rate of the forward reaction becomes equal to the rate of the reverse reaction at the equilibrium stage
   ${\mathrm{R}}_{\mathrm{f}}={\mathrm{R}}_{\mathrm{r}}$
6. However, the rate of formation of reactants and the rate of formation of products does not stop and it keeps on forming at the same rate.