In order to calculate the equilibrium concentrations of compounds we need to use an ICE Chart.
Concept #1: Understanding an ICE Chart
An ICE Chart should be used when we are missing more than one equilibrium amount for compounds in our balanced equation.
Since our equilibrium constant K is involved in an ICE Chart then we must continue to ignore solids and liquids.
Example #1: We have a solution where Ag(CN)2 –(g), CN – (g), and Ag+ (g) have an equilibrium constant, K, equal to 1.8 x 10-19. If the equilibrium concentrations of Ag(CN)2 – and CN – are 0.030 and 0.10 respectively, what is the equilibrium concentration of Ag+?
Example #2: We place 2.5 mol of CO and 2.5 mol of CO3 in a 10.0 L flask and let the system come to equilibrium. What will be the final concentration of CO2? K = 0.47
Practice: For the reaction: N2 (g) + 2 O2 (g) ⇌ 2 NO2 (g), Kc = 8.3 x 10 -10 at 25°C. What is the concentration of N2 gas at equilibrium when the concentration of NO2 is twice the concentration of O2 gas?
Example #3: When 0.600 atm of NO2 was allowed to come to equilibrium the total pressure was 0.875 atm. Calculate the Kp of the reaction.
Example #4: An important reaction in the formation of acid rain listed below.
2 SO2 (g) + O2 (g) ⇌ 2 SO3 (g)
Initially, 0.023 M SO2 and 0.015 M O2 are mixed and allowed to react in an evacuated flask at 340 oC. When an equilibrium is established the equilibrium amount of SO3 was found to be 0.00199 M. Calculate the equilibrium constant, Kc, for the reaction at 340 oC.
Example #5: If Kc is 32.7 at 300oC for the reaction below:
H2 (g) + Br2 (g) ⇌ 2 HBr (g)
What is the concentration of H2 at equilibrium if a 20.0 L flask contains 5.0 mol HBr initially?
Practice: At a given temperature the gas phase reaction: N2 (g) + O2 (g) ⇌ 2 NO (g) has an equilibrium constant of 4.00 x 10 -15. What will be the concentration of NO at equilibrium if 2.00 moles of nitrogen and 6.00 moles oxygen are allowed to come to equilibrium in a 2.0 L flask.
Example #6: Consider the following reaction:
COBr2 (g) ⇌ CO (g) + Br2 (g)
A reaction mixture initially contains 0.15 M COBr2. Determine the equilibrium concentration of CO if Kc for the reaction at this temperature is 2.15 x 10-3.