# Using a RICE Table in Equilibrium Calculations Video

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• 0:05 RICE Table
• 1:16 Solve for Amounts of Reactants
• 2:59 Solve for Keq
• 5:36 Lesson Summary
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Lesson Transcript
Instructor: Amy Meyers

Amy holds a Master of Science. She has taught science at the high school and college levels.

Learn what the RICE table is and how to fill in the table with the reaction, initial concentration, change in concentration and amount of product and reactants at equilibrium. Learn how to use the RICE table to calculate the concentrations and amounts and the equilibrium constant of equations at equilibrium.

## Rice Table

You know how to use the equilibrium constant, Keq, to solve for the concentrations of products and reactants in a reaction that reaches equilibrium. There is a lot of information that you need to keep track of. One way scientists do it is with the RICE table, sometimes known as the ICE table.

The RICE table is a way of keeping track of the data generated in an equilibrium reaction.

R stands for reaction.

I stands for initial amounts.

C stands for change in amounts due to reaction.

E stands for equilibrium (amounts of reactants and products at equilibrium).

A rice table looks like this:

R Concentration of reactant Concentration of reactant Concentration of product
I
C
E

To use the table, do the following steps:

1. Write the balanced chemical equation.
2. Set up the RICE table and fill it in.
3. Write the equilibrium expression Keq = (concentration of product) / (concentration of reactant).
4. Solve the equilibrium problem.

## Use the RICE Table to Solve for Amounts of Reactants

This is what it looks like in action:

In the reaction 2A<==>2B + C, you start with 0.50 moles of A and no quantity of B and C. The Keq = 5 x 10^-5.

Keq = [(B)^2 * (C)] / (A)^2

At the beginning of the reaction, there are no products, so the reaction must move to the right to make some and reach equilibrium. We can let X equal the change in amount for the substances to reach equilibrium. For product C, there is only one molecule, so the amount just equals X.

2A = 2B + C

2X = 2X + X

The table is set up as follows:

R Amount of A Amount of B Amount of C
I 0.5 0.0 0.0
C -2X +2X +X
E 0.5-2X 2X X

When you take these numbers and put them in the equilibrium equation, it becomes:

5 x 10^-5 = [(2X)^2 * (X)] / [(0.5 - 2X)^2]

This simplifies to:

X^3 = [(5 x 10^-5)*(0.5)^2] / 4

Which simplifies to:

X = 0.0146

Now, you can put the value of X back into the table and that will tell you everything's amount:

R Amount of A Amount of B Amount of C
I 0.5 0.0 0.0
C -2(0.0146) = -0.03 +2(0.0146) = 0.03 +0.0146
E 0.5-2(0.0146) = 0.47 2(0.0146) = 0.03 0.0146

The amount of A at equilibrium is 0.47. B at equilibrium is 0.03, and the amount of C is 0.0146.

## How to Use the RICE Table to Solve for Keq

Now, try a calculation where we don't have the Keq.

For the reaction 2X <==> 3Y + 2Z, you begin with a 1.5 L volume solution in which there are 0.5 moles of X to start and 0.25 moles of X when the reaction equals equilibrium. What is the Keq?

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