Equilibrium Constant Formula

The Formula

K_{eq} = \frac{[\text{products}]}{[\text{reactants}]}

When to use: A large K means products are favored; a small K means reactants are favored.

Quick Example

For A ⇌ B, if K = 100, at equilibrium there is 100 times more B than A.

What This Formula Means

A numerical value expressing the ratio of product concentrations to reactant concentrations at equilibrium.

A large K means products are favored; a small K means reactants are favored.

Why This Formula Matters

Predicts reaction yield, solubility, and acid–base behavior in chemical systems.

Frequently Asked Questions

What is the Equilibrium Constant formula?

A numerical value expressing the ratio of product concentrations to reactant concentrations at equilibrium.

How do you use the Equilibrium Constant formula?

A large K means products are favored; a small K means reactants are favored.

Why is the Equilibrium Constant formula important in Chemistry?

Predicts reaction yield, solubility, and acid–base behavior in chemical systems.

What do students get wrong about Equilibrium Constant?

Pure solids and liquids are excluded from the equilibrium expression.

What should I learn before the Equilibrium Constant formula?

Before studying the Equilibrium Constant formula, you should understand: equilibrium, concentration.