Equilibrium Constants and Calculations
This final section focuses on the quantitative aspects of chemical equilibrium, introducing the concept of equilibrium constants and their calculations.
The equilibrium constant (K) is defined as the ratio of the concentrations of products to reactants, each raised to the power of their stoichiometric coefficients. Two types of equilibrium constants are discussed:
- Kc: Concentration-based equilibrium constant
- Kp: Pressure-based equilibrium constant (for gas-phase reactions)
Definition: The equilibrium constant (K) is a quantitative measure of the extent of a reaction at equilibrium, expressed as the ratio of product concentrations to reactant concentrations, each raised to the power of their stoichiometric coefficients.
The relationship between Kc and Kp is explained using the ideal gas equation:
Kp = Kc(RT)^Δn
Where:
- R is the gas constant
- T is the absolute temperature
- Δn is the change in the number of moles of gas
Highlight: The relationship between Kc and Kp depends on the change in the number of moles of gas in the reaction.
The chapter concludes with an example calculation involving the Haber process, demonstrating how to determine Kp from Kc using the given equation.
Example: For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), Δn = 2 - (1 + 3) = -2. Therefore, Kp = Kc(RT)^(-2).
This comprehensive guide provides a solid foundation for understanding chemical equilibrium and reaction energy, essential topics for 11th-grade chemistry and the AYT Chemistry exam.
