ICE Tables: Introduction

ICE tables are useful for organizing large amounts of information about the starting and ending amounts of reactants and products in a chemical reaction. Below are some sample questions and the completed ICE tables that are used to solve them.

1. In a general chemistry laboratory experiment, a student prepares aspirin (acetylsalicylic acid, HC₉H₇O₄, abbreviated HAc) by reacting salicylic acid, C₇H₆O₃ (abbreaviated Sal.Ac.), with acetic anhydride, C₄H₆O₃ (Ac.An.):

2 C₇H₆O₃ (s) + C₄H₆O₃ (l) 2 HC₉H₇O₄ (s) + H₂O (l)

The laboratory manual says to use 2.0 g of salicylic acid and 5.4 g of acetic anhydride. What is the maximum mass of aspirin that can be prepared?

	2 Sal.Ac.	+ Ac.An.		2 HAc	+ H2O
I	0.0145	0.0529		0	0
C	-0.0145	-.00725		0.0145	0.00725
E	0	0.04565		0.0145	0.00725

2. There are 324 mg of aspirin (M = 180.15 g/mol) per aspirin tablet. If two tablets are dissolved in water to give two ounces (about 59 mL) of solution, estimate the pH. The K_a of aspirin is 3.6 x 10^-4.

	HAc		Ac-	+ H+
I	0.06097		0	0
C	-x		+x	+x
E	0.06097 - x		x	x

ICE tables are useful when the amount of one reactant or product must be determined from given information about another reactant or product. Sometimes, the answers to questions of interest can be directly determined from one or more entries in an ICE table. More often, the amounts in an ICE table connect to some other transformation that can answer the question. For example, in question 1, the ending amount of aspirin, provided in moles in the ICE table, can be converted to grams to determine the yield of aspirin in grams. In question 2, the expressions for the equilibrium concentrations can be substituted into the expression equivalent to K_a. This expression can be solved for x, which is equal to the hydrogen ion concentration, which can be converted to pH.