Finding Concentration when a System Reaches Equilibrium

This is the mathematical heart of Equilibrium, and there are a number of ways that these problems can appear and therefore a number of methods for solving them.

Before we can start, you need to understand:

1. How to write the equilibrium expression

2. How to determine which direction the system will shift in order to reach equilibrium

3. Significant figures, and especially the rules for addition and subtraction

4. The basic ideas of stoichiometry

Before you can solve any of these problems, you will need to understand how to set up an ICE table.

You also need to understand what the terms "big" and "little" mean. Specifically, you need to know what it means when K is big and what it means when K is little. You also need to understand what it means when "x" is big and when "x" is little.

Once you have an ICE table, there are three types of problems you will face

1. Squares and cubes

2. Little “x” problems

3. Big “X” problems (These are the least common, and depending on your course and instructor, you may not need to solve these but understanding the ideas will be important when you study strong and weak acids and bases.)