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ICE Bases

ICE table and calculations are done when working with bases, similar to those used for acids, but you need to write OH- instead of H3O+ and use the base dissociation constant (Kb), instead of Ka.

A table that can be used to calculate the concentrations of base, hydroxide ions, and conjugate acid at the three different stages of a reaction of an acid with water. The reaction stages are I, the initial phase, C the change phase, and E, the equilibrium phase. The table contents are as follows. Base concentrations: during initial phase, equal to C subscript B, which is the initial base concentration, during change phase, equals negative X, which is the concentration change during dissociation, during the equilibrium phase, equals C subscript B minus X. Hydroxide ion concentrations: during initial phase, equals zero, during the change phase, equals positive X, and during the equilibrium phase, equals X. Conjugate acid concentration: during the initial phase, equals zero, during the change phase, equals positive X, and during the equilibrium phase, equals X. For a strong base, X is equal to the initial concentration of the base. For a weak base, X must be calculated using the formula for the base dissociation constant, which is Kb equals the concentration of conjugate acid times the concentration of hydroxide ions, divided by the base concentration. After substituting the concentration values for those located in the equilibrium phase of the ICE chart, the equation becomes Kb equals X times X divided by the initial concentration of base minus X. This equation can then be rearranged to X squared plus the base dissociation constant times X minus the base dissociation constant times the initial concentration of base equals zero. This equation can then be solved for X and the ICE table can be filled out with the value of X.

Notice that x can be approximated to Cb when it is a strong base since they are totally protonated. For weak bases, X must be calculated using the formula for base dissociation constant.

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