Question

Which of the following statements about equilibrium of chemical reactions is correct?

a) Equilibrium occurs when reactants and products are equal in concentration.
b) Equilibrium means the reaction has stopped completely.
c) Equilibrium is only achieved in reversible reactions.
d) Equilibrium can only occur in the absence of a catalyst.

Answer 1

Equilibrium is achieved in reversible reactions where the rate of the forward reaction equals the rate of the reverse reaction, resulting in constant concentrations of reactants and products without implying their concentrations are equal.

Step-by-step explanation:

The correct statement about equilibrium of chemical reactions is that equilibrium is achieved in reversible reactions, which is choice C. In chemical reactions, equilibrium is a dynamic state where the rate of the forward reaction equals the rate of the reverse reaction. This means that while the concentrations of reactants and products remain constant, the reaction itself has not stopped; it continues at equal rates in both directions. Therefore, seeing a constant concentration of reactants and products does not mean they are equal in concentration; it signifies that their concentrations are no longer changing over time.

Statement A is incorrect because equilibrium does not require that reactants and products have equal concentrations. Statement B is incorrect because at equilibrium, the reaction has not stopped; it continues dynamically. Statement D is false because the presence or absence of a catalyst does not prevent a reaction from reaching equilibrium.