Sample Equilibrium Problems
1) Calculating K.
A) N2O4  2NO2
At equilibrium [N2O4] = 0.00140M and [NO2] = 0.0172M
Calculate Kc.
B) CaCO3(s)  CaO(s) + CO2(g)
At equilibrium [CO2] = 0.0500 atm.
Calculate Kp.
2) Calculating unknown Concentration.
N2 + 3H2  2NH3
Kc= 0.105
At equilibrium a 1.0 liter bottle contains .090 mol N2 and .070 mol H2. What is the
equilibrium concentration of the NH3??
3) Determining if a system is at equilibrium.
A 2.00 liter container is filled with 2.00 mol of H2, 1.00 mol N2 and 2.00 mol of NH3. Is
this system at equilibrium????
4) Calculate K when only 1 equilibrium concentration is given.
2SO3  2SO2 + O2
Initial Concentration of SO3 is 0.00609 M. Equilibrium Concentration of SO3 is
0.00244M. Calculate the value of K.
5) Calculate Equilibrium conc when only initial concentrations and K are given.
Note if initial concentration of all species are present, then you must calc
Q to determine the direction the reaction will proceed.
A2
+
B2

Initial concentrations: 0.100M
0.100M
2AB
0.100M
K= 0.567
After this system reaches equilibrium, what will be the concentrations of all reactants and
products?
6) Calculate K when all initial concentrations are given along with equilibrium
concentration of at least one reactant or product.
1A + 2B  1AB2
0.10 mols of each A, B and AB2 are placed in a 3.0 liter container. When equilibrium is
reached 0.050 mols of AB2 are present. Determine the value of Keq.
7) One more for fun.
PCl5 
PCl3 + Cl2
Kp = 0.497
The initial pressure of PCl5 = 1.66 atm. What will be the equilibrium pressure of all
gases in this system.