A chemist trying to synthesize a particular compound attempts two different synthesis reactions. The equilibrium constants for the two reactions are 23.3 and 2.2⨉10⁴ at room temperature. However, upon carrying out both reactions for 15 minutes, the chemist finds that the reaction with the smaller equilibrium constant produces more of the desired product. Explain how this might be possible.

Key Concepts

Equilibrium Constant (K)

The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. A higher K value indicates a greater tendency for the reaction to favor product formation, while a lower K suggests a preference for reactants. However, K does not provide information about the rate of the reaction or how quickly equilibrium is reached.

Reaction Rate

The reaction rate refers to the speed at which reactants are converted into products in a chemical reaction. It is influenced by factors such as concentration, temperature, and the presence of catalysts. Even if a reaction has a lower equilibrium constant, it may proceed at a faster rate initially, allowing it to produce more product before reaching equilibrium compared to a slower reaction with a higher K value.

Time to Reach Equilibrium

The time it takes for a reaction to reach equilibrium can vary significantly between different reactions. Some reactions may reach equilibrium quickly, while others take longer. In the scenario described, the reaction with the smaller equilibrium constant may have produced more product in the short term (15 minutes) due to its faster reaction kinetics, despite having a lower overall yield at equilibrium.