Final answer:
The reaction quotient (Q) is a measure used to quantify the relative amounts of reactants and products during a reversible chemical reaction before the system has reached equilibrium.
Step-by-step explanation:
The reaction quotient (Q) is a mathematical function used to evaluate the status of a reversible reaction at any point before the system reaches equilibrium. This quantity is calculated using the concentrations or pressures of the reactants and products in a reaction mixture. Specifically, for a balanced chemical equation aA + bB → cC + dD, the reaction quotient (Q) is expressed as Qc = [C]^c[D]^d / [A]^a[B]^b for concentrations (Qc), or Qp = P_C^cP_D^d / P_A^aP_B^b for partial pressures (Qp). The reaction quotient is an essential tool in predicting the direction in which a reaction will proceed to reach equilibrium.