Intermediate Topic 470 of 1102 Kinetics & Equilibrium
ICE Tables
A method tracking initial, change and equilibrium concentrations to solve equilibrium problems.
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In-depth explanation of ICE Tables
An ICE table is a systematic bookkeeping method for solving equilibrium problems, with rows labelled Initial, Change and Equilibrium. The initial concentrations are written first, then the change in each species is expressed in terms of a single unknown x according to the stoichiometric coefficients, and finally the equilibrium concentrations are found by adding the change to the initial values. These expressions are substituted into the equilibrium constant expression and solved for x. When K is small, x is often much smaller than the initial concentration, so the expression can be simplified, and this approximation should be checked with the five percent rule.
Going deeper: ICE Tables
Key ideas: Steps: write balanced equation, fill the initial row, define change as +x or -x times coefficients, form equilibrium row, substitute into K, solve for x. Use the approximation x much smaller than initial when K is below about 10^-3 times concentration, and then verify x is under 5 percent of the initial. Otherwise solve the quadratic and reject negative or too large roots.
Common mistakes and connections: A frequent mistake is forgetting to multiply x by the coefficient, or to raise it to the power in K. Students also use the approximation without checking, giving large errors. Another is placing solids in the table. If Q is greater than K, change is negative for products, so check the direction using Q first. Tables are also used for acid-base and solubility problems.
Visualization of ICE Tables
For a weak acid with K = 1.8e-5 at 0.10 M, x is only 0.0013 M, under 5 percent of 0.10, so the small-x approximation is valid. The interactive lesson shows this as a live animation or chart.
Worked example and use case
For a weak acid with K = 1.8 x 10^-5 at 0.10 M, the ICE table gives x of about 1.3 x 10^-3 M, which is under 5 percent of 0.10 M.
Frequently asked questions about ICE Tables
What is ICE Tables?
A method tracking initial, change and equilibrium concentrations to solve equilibrium problems.
Is ICE Tables a beginner, intermediate or advanced topic?
ICE Tables is a intermediate topic in Kinetics & Equilibrium. It builds on the vocabulary of beginner topics in this area.
What should I learn before ICE Tables?
Study these earlier topics in Kinetics & Equilibrium first: Magnitude of K, Homogeneous and Heterogeneous Equilibria, Manipulating K.
What comes after ICE Tables?
The next topics in Kinetics & Equilibrium are Le Chatelier's Principle and Effect of Concentration on Equilibrium.
Can I practise ICE Tables with quizzes?
Yes. The interactive lesson includes a self-check question on ICE Tables, and the Kinetics & Equilibrium quiz draws on every topic in this area.
Where ICE Tables fits in Kinetics & Equilibrium
ICE Tables is topic 51 of 91 in Kinetics & Equilibrium.