Final answer:
When calculating the equilibrium constant (Keq), you need to insert the equilibrium concentrations for all the reactants and products involved in the chemical reaction. These concentrations can be determined using the initial amounts and the given value of Keq.
Step-by-step explanation:
When calculating the equilibrium constant (Keq), you need to insert the equilibrium concentrations for all the reactants and products involved in the chemical reaction. These concentrations can be determined using the initial amounts and the given value of Keq. For example, if you have the equation: A + B <-> C and the value of Keq is 2.0, if the concentration of B is 4.0 M, then the concentration of A must be 2.0 M to satisfy the equilibrium expression.