Ice tables

Science

Definition

ICE tables (Initial, Change, Equilibrium) are an organized method for calculating the concentrations of reactants and products at equilibrium. They help solve for unknown equilibrium concentrations or pressures using the equilibrium constant expression.

How It Works

  1. Write the balanced chemical equation for the reaction.
  2. Fill in the Initial concentrations (or pressures) of all species.
  3. Define the Change row using a variable x based on the stoichiometric coefficients (−x for reactants, +x for products, adjusted by coefficients).
  4. Express the Equilibrium concentrations as Initial + Change for each species.
  5. Substitute the equilibrium expressions into the K expression and solve for x.
  6. Calculate the final equilibrium concentrations by plugging x back into the equilibrium row.

Examples

  • Finding the equilibrium concentrations in the reaction N₂ + 3H₂ ⇌ 2NH₃ given initial amounts and Kc
  • Determining the pH of a weak acid solution by setting up an ICE table with Ka
  • Calculating the solubility of a sparingly soluble salt using an ICE table with Ksp
Key Fact

ICE = Initial, Change, Equilibrium; always use stoichiometric ratios to relate changes across species.

Related Terms

Equilibrium constant Le chatelier's principle Concentration Ph calculations

Study This Concept

Practice ICE tables with free review games in these units:

AP Chemistry Unit 7: Equilibrium