An ICE table or RICE box or RICE chart is a tabular system of keeping track of changing concentrations in an equilibrium reaction.
It is used in chemistry to keep track of the changes in amount of substance of the reactants and also organize a set of conditions that one wants to solve with.
[2] Others simply call it a concentration table (for the acid–base equilibrium).
[3] To illustrate the processes, consider the case of dissolving a weak acid, HA, in water.
The columns of the table correspond to the three species in equilibrium.
The first row shows the reaction, which some authors label R and some leave blank.
The third row, labeled C, specifies the change that occurs during the reaction.
This follows from consideration of mass balance (the total number of each atom/molecule must remain the same) and charge balance (the sum of the electric charges before and after the reaction must be zero).
Note that the coefficients in front of the "x" correlate to the mole ratios of the reactants to the product.
For example, if the reaction equation had 2 H+ ions in the product, then the "change" for that cell would be "2x" The fourth row, labeled E, is the sum of the first two rows and shows the final concentrations of each species at equilibrium.
Substitute the concentrations with the values found in the last row of the ICE table.
With specific values for Ca and Ka this quadratic equation can be solved for x.
If the degree of dissociation is quite small, Ca ≫ x and the expression simplifies to
This approximate expression is good for pKa values larger than about 2 and concentrations high enough.