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Equilibrium Constant Formula:
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The equilibrium constant (K) quantifies the ratio of product concentrations to reactant concentrations at equilibrium, raised to their stoichiometric coefficients. It's related to the standard Gibbs free energy change (ΔG°) of the reaction.
The calculator uses the thermodynamic relationship:
Where:
Explanation: The equation shows that reactions with negative ΔG° (spontaneous under standard conditions) have K > 1, favoring products, while positive ΔG° gives K < 1, favoring reactants.
Details: The equilibrium constant is fundamental in chemical thermodynamics, predicting reaction direction, extent, and composition of equilibrium mixtures. It's essential for industrial process design and biochemical systems.
Tips: Enter ΔG° in J/mol and temperature in Kelvin. Standard temperature is 298.15 K (25°C). The result is dimensionless and applies to the reaction as written.
Q1: What's the difference between K and Q?
A: K is the equilibrium constant for standard conditions, while Q is the reaction quotient for current conditions. Comparing Q to K predicts reaction direction.
Q2: How does temperature affect K?
A: For endothermic reactions (ΔH° > 0), K increases with temperature. For exothermic reactions (ΔH° < 0), K decreases with temperature.
Q3: What if ΔG° = 0?
A: When ΔG° = 0, K = 1, meaning products and reactants are equally favored at standard conditions.
Q4: Can this be used for electrochemical cells?
A: Yes, ΔG° = -nFE° relates to electrode potentials, allowing calculation of equilibrium constants for redox reactions.
Q5: What are typical K values?
A: K can range from very small (<10⁻¹⁰) to very large (>10¹⁰). Values between 10⁻³ and 10³ often represent chemically significant equilibria.