Equilibrium Concentration Calculations: ICE Tables

Introduction to ICE Tables

ICE stands for Initial, Change, and Equilibrium.
Used in equilibrium concentration calculations when initial concentrations are provided.
I (Initial): Concentration or pressure of all species at the start of the reaction (products initially at 0).
C (Change): Denoted by a negative sign for reactants (consumed) and positive for products (formed).
E (Equilibrium): Sum of initial concentration and the change.

Start with Balanced Chemical Equation: Coefficients determine the magnitude of change.
Set Up ICE Table:
- Rows: I, C, E
- Columns: Species involved in the reaction
Write Equilibrium Expression: Based on the balanced chemical equation.
Calculate Reaction Quotient: Determines if the system is at equilibrium or needs to shift.

Given Reaction at 700K: Start with 1.0 mole CO and 1.0 mole H2O in a 5L container.
Goal: Find moles of each substance at equilibrium if K_eq = 0.83.

Check Balance of Reaction: Ensure all elements are balanced.
Determine Initial Concentrations:
- Using formula C = n/V: 1.0 mole / 5L = 0.20 M for both CO and H2O.
- Products start at 0 M.
Set Up ICE Table with CO, H2O, H2, and CO2:
- I: 0.20 M for reactants, 0 for products.
- C: -x for reactants, +x for products.
- E: 0.20 - x for reactants, x for products.
Write K_eq Expression:
- K_eq = [H2][CO2] / [CO][H2O] = x^2 / (0.20 - x)^2 = 0.83
Solve for x:
- Simplify using perfect squares: 0.83 = x^2 / (0.2 - x)^2.
- Square root both sides to solve for x.
- Result: x ≈ 0.09534 M
Calculate Equilibrium Concentrations:
- Reactants: 0.20 - x = 0.1046 M
- Products: x = 0.09534 M
Convert to Moles:
- Use c = n/V to convert concentrations to moles.
- Reactants and products moles calculated.

At equilibrium, CO and H2O are each 0.52 moles; H2 and CO2 are each 0.48 moles.
Consistent with K_eq value indicating greater concentration of reactants than products.
Next Topic: Handling quadratic equations in ICE tables when perfect squares are not applicable.