Not Quite at Equilibrium - Ice Calculations

NOT QUITE AT EQUILIBRIUM - ICE CALCULATIONS

A reversible reaction that takes place in a closed container will eventually reach equilibrium. Equilibrium takes some time to occur and does not happen instantly.

So far, we have done calculations with Keq based on the concentrations of reactants and products of reactions that were already at equilibrium.

The next examples involve determining Keq from reactions that provide us with initial concentrations and not all of the equilibrium (or final) concentrations. These calculations involve making an ICE chart.

In Class Example 1 A:

Given the following equilibrium system: 3 B(g) + A(g) ó 2 C(g)

The initial [B] = 0.30 M and initial [A] = 0.10 M. Once equilibrium was reached [A] = 0.08 M

Find the equilibrium concentrations of B and C and calculate Keq.

initial
change
equilibrium

Practice Question 1 B:

Given the Haber process for synthesizing ammonia: ______

The initial [N2] is 0.32 M and [H2] is 0.66 M and at equilibrium [H2] = 0.30 M

Find the equilibrium [N2] and [NH3] and calculate Keq.

initial
change
equilibrium

In Class Example 2 A:

2 HI(g) « H2 (g) + I2 (g) Keq = 0.016

If we start with 0.010 mol/L of H2 and I2 and 0.096 mol/L of HI, what are their concentrations at equilibrium?

initial / / /
change / / /
equilibrium / / /

Practice Question 2 B:

For the system: CO2(g) + H2(g) « CO(g) + H2O(g) Keq = 0.64 at 900K

If we start with 0.100mol/L of CO2 and H2, what are the concentrations of the reactants and products at equilibrium?

initial
change
equilibrium

Practice Question 2 C: Consider the reaction SO2(g) + NO2(g) ↔NO(g) + SO3(g). In a 1.0L container, 0.017 mol of SO2(g) and 0.011 mol of NO2(g) were added. The value of Keq for the reaction at 200K is 4.8. What is the equilibrium concentration of SO3(g) at this temperature?