The number of reactants and products in chemical equilibrium do not have to be the same. Chemical equilibrium is a state where the rate of the forward reaction is equal to the rate of the reverse reaction, which means that the concentrations of reactants and products will remain constant over time. The equilibrium constant (K) is a ratio of the concentrations of the products and reactants at equilibrium, and it does not depend on the stoichiometry of the reaction. Therefore, the number of reactants and products in chemical equilibrium can vary, as long as the concentrations of all species remain constant at the equilibrium state.