Qc

This is the reaction quotient expressed in terms of concentrations of reactants and products. It is used to determine whether a reaction is at equilibrium by comparing its value to the equilibrium constant (Kc). If Qc is equal to Kc, the reaction is at equilibrium. If Qc is greater than Kc, the reaction will shift in the reverse direction to reach equilibrium. If Qc is less than Kc, the reaction will shift in the forward direction to reach equilibrium.