Equilibrium Constants and Their Applications
The Equilibrium Constant ($K$)
- As discussed in the previous section, the equilibrium constant $K$ is a quantitative measure of the position of equilibrium for a chemical reaction.
- It is expressed as:
$$
K = \frac{[\text{Products}]^{\text{stoichiometric coefficients}}}{[\text{Reactants}]^{\text{stoichiometric coefficients}}}
$$
The magnitude of $K$ provides valuable information about the extent of a reaction at equilibrium.
- When $K << 1$: Reactants are Favored
- A very small $K$ value (e.g., $K = 10^{-5}$) indicates that the equilibrium position is heavily skewed toward the reactants.
- Only a small proportion of reactants has been converted into products.
- When $K \approx 1$: Comparable Amounts of Reactants and Products
- When $K$ is close to 1 (e.g., $K = 0.8$), there are significant amounts of both reactants and products at equilibrium.
- Neither direction of the reaction is strongly favored.
- When $K >> 1$: Products are Favored
- A large $K$ value (e.g., $K = 10^5$) means the equilibrium position is strongly shifted toward the products.
- Most reactants are converted into products.
