Chemical Equilibrium: Videos & Practice Problems

Chemical equilibrium is a state in a chemical reaction where the concentrations of reactants and products remain constant over time. This occurs because the forward and reverse reactions happen at the same rate. In a reversible reaction, reactants convert to products and products convert back to reactants simultaneously. When the rate of the forward reaction equals the rate of the reverse reaction, the system reaches equilibrium. At this point, the amounts of reactants and products do not change, even though molecular activity continues. This balance can be visualized in concentration plots where both reactants and products plateau.

A reaction has reached chemical equilibrium when the concentrations of reactants and products remain constant over time. This can be observed in a concentration vs. time plot where the lines representing the amounts of reactants and products plateau. At equilibrium, the forward and reverse reactions occur at the same rate, so there is no net change in the concentrations of reactants and products. Although molecular activity continues, the overall amounts of reactants and products stay the same, indicating that equilibrium has been achieved.

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction. It is a crucial parameter that indicates the extent to which a reaction proceeds. A large K value (K > 1) suggests that the reaction favors the formation of products, while a small K value (K < 1) indicates that reactants are favored. The equilibrium constant is specific to a particular reaction at a given temperature and provides insight into the reaction's dynamics and the relative stability of reactants and products.

Most chemical reactions do not go to completion because they are reversible, meaning the products can revert back to reactants. In such reactions, the forward and reverse processes occur simultaneously. As the reaction progresses, the rate of the forward reaction decreases while the rate of the reverse reaction increases until they become equal. At this point, the system reaches chemical equilibrium, and the concentrations of reactants and products remain constant. This dynamic balance prevents the complete conversion of reactants into products, resulting in some amount of reactants always being present.

At equilibrium, the concentrations of reactants and products remain constant over time. This occurs because the forward and reverse reactions happen at the same rate, leading to no net change in the amounts of reactants and products. Although molecular activity continues, the overall concentrations do not vary. This state of balance is visually represented in concentration plots where the lines for reactants and products plateau, indicating that their levels have stabilized and equilibrium has been achieved.