Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
a. The concentrations of products and reactants are equal.
b. The reaction is now irreversible.
c. Both forward and reverse reactions have halted.
d. The rates of the forward and reverse reactions are equal.

Verified step by step guidance

1. Understand the concept of chemical equilibrium: In a chemical reaction, equilibrium is reached when the rate of the forward reaction equals the rate of the reverse reaction.
2. Analyze statement (A): 'The concentrations of products and reactants are equal.' This is incorrect because equilibrium does not imply equal concentrations, but rather equal rates of the forward and reverse reactions.
3. Analyze statement (B): 'The reaction is now irreversible.' This is incorrect because at equilibrium, reactions are reversible, and both forward and reverse reactions continue to occur.
4. Analyze statement (C): 'Both forward and reverse reactions have halted.' This is incorrect because at equilibrium, both reactions continue to occur at equal rates, not halted.
5. Analyze statement (D): 'The rates of the forward and reverse reactions are equal.' This is correct because at equilibrium, the rates of the forward and reverse reactions are indeed equal, allowing the concentrations of reactants and products to remain constant.

Key Concepts

Chemical Equilibrium

Chemical equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in the concentrations of reactants and products. It is a dynamic state where reactions continue to occur, but the overall concentrations remain constant.

Reaction Rates

Reaction rates refer to the speed at which reactants are converted into products in a chemical reaction. At equilibrium, the rates of the forward and reverse reactions are equal, meaning that the processes are ongoing but balanced, maintaining constant concentrations of substances involved.

Concentration of Reactants and Products

In a chemical reaction at equilibrium, the concentrations of reactants and products are not necessarily equal, but they remain constant over time. This stability is due to the equal rates of the forward and reverse reactions, allowing the system to maintain a steady state without further net change.