Calculate Equilibrium Constant From Delta G

Equilibrium Constant Formula:

\[ K_c = e^{-\frac{\Delta G}{RT}} \]

Equilibrium Constant (K_c):

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1. What is the Equilibrium Constant?

The equilibrium constant (K_c) quantifies the ratio of product concentrations to reactant concentrations at equilibrium, each raised to the power of their stoichiometric coefficients. It's a fundamental concept in chemical thermodynamics that predicts the direction and extent of chemical reactions.

2. How Does the Calculator Work?

The calculator uses the thermodynamic relationship:

\[ K_c = e^{-\frac{\Delta G}{RT}} \]

Where:

\( K_c \) — Equilibrium constant (unitless)
\( \Delta G \) — Gibbs free energy change (kJ/mol)
\( R \) — Gas constant (8.314 J/(mol·K))
\( T \) — Absolute temperature (K)

Explanation: The equation relates the thermodynamic driving force (ΔG) to the position of equilibrium. A negative ΔG favors products (K > 1), while a positive ΔG favors reactants (K < 1).

3. Importance of Equilibrium Constant

Details: K_c is crucial for predicting reaction outcomes, designing chemical processes, and understanding biochemical systems. It helps determine whether a reaction is product-favored or reactant-favored under standard conditions.

4. Using the Calculator

Tips: Enter ΔG in kJ/mol and temperature in Kelvin. The temperature must be positive. Default temperature is 298.15 K (25°C) for standard conditions.

5. Frequently Asked Questions (FAQ)

Q1: What does a large K_c value mean?
A: K_c > 1 indicates products are favored at equilibrium. The larger the value, the more complete the reaction.

Q2: How does temperature affect K_c?
A: For endothermic reactions (ΔH > 0), K_c increases with temperature. For exothermic reactions (ΔH < 0), K_c decreases with temperature.

Q3: What's the difference between K_c and K_p?
A: K_c uses concentrations (mol/L), while K_p uses partial pressures (atm) for gas-phase reactions.

Q4: Can this equation be used for non-standard conditions?
A: This calculates standard K (ΔG°). For non-standard conditions, use ΔG = ΔG° + RTlnQ.

Q5: What are typical K_c values?
A: Values range from very small (<10^-10) to very large (>10¹⁰). K_c = 1 indicates equal concentrations of products and reactants at equilibrium.