Calculate K at 298 K for The Following Reaction:

Introduction

The equilibrium constant (K) is a measure of the ratio of products to reactants at equilibrium in a chemical reaction. For reactions at 298 K (25°C), we use the standard Gibbs free energy change (ΔG°) to calculate K.

This calculator helps you determine K for any reaction given the standard Gibbs free energy change and temperature.

How to Use This Calculator

1. Enter the standard Gibbs free energy change (ΔG°) in kilojoules per mole (kJ/mol).
2. Click "Calculate K" to compute the equilibrium constant.
3. Review the result and interpretation.
4. Use the "Reset" button to clear inputs and start over.

The Formula

The equilibrium constant (K) at 298 K is calculated using the following formula:

This formula comes from the relationship between Gibbs free energy and equilibrium constants.

Worked Example

Let's calculate K for a reaction with ΔG° = -20 kJ/mol.

1. Convert ΔG° to joules: -20 kJ/mol = -20,000 J/mol.
2. Plug into the formula: K = e^(-(-20,000) / (8.314 * 298))
3. Calculate the exponent: 20,000 / (8.314 * 298) ≈ 8.33
4. Compute e^8.33 ≈ 4,500

The equilibrium constant K is approximately 4,500.

Interpreting Results

A large K value (>>1) indicates the reaction strongly favors products. A small K value (<<1) indicates the reaction strongly favors reactants. A K value near 1 indicates a balanced equilibrium.

Always consider the reaction's context when interpreting K values.