Equilibrium Calculations – Calculating Equilibrium constants - 2
For each of the following problems calculate the required equilibrium constant. Show your
work in the spaces provided.
1. One mole of hydrogen and one mole of iodine are sealed in a 1 dm3 flask and allowed
to come to equilibrium. At equilibrium 1.56 mole of hydrogen iodide is present.
H2 (g) + I2 (g) 2 HI (g)
What are the equilibrium concentrations of I2 (g) and H2 (g)? What is the equilibrium
2. For the reaction: H2 (g) + I2 (g) 2 HI (g), at a certain temperature the
equilibrium concentrations of H2 and I2 are both 0.15 M and that of HI is 0.50 M.
Calculate the equilibrium constant at this temperature.
3. The following equilibrium represents the formation of hydrogen iodide :
H2 (g) + I2 (g) 2 HI (g)
The value of kc for this reaction 50.3 at 450 oC . If 2.0 mole of H2 and 2.0 mole of I2 are
placed in a sealed container and allowed to come to equilibrium, calculate the equilibrium
concentrations of [H2], [I2], and [HI]
4. At 500 oC the equilibrium constant kc for the following reaction is 0.0224
PCl3 (g) + Cl2 (g).
Suppose that 1.0 mole of PCl5 is placed in a 2.0 dm3 and allowed top come to
equilibrium. Calculate the equilibrium concentrations of [PCl5], [PCl3], and [Cl2]
5. An analysis of the concentrations at equilibrium in a l dm3 flask yields the following
results: [NOCl ] = 0.30 mol, [NO ] = 1.2 mol, and [Cl2] = 0.60 mol
2 NOCl (g) 2 NO (g) + Cl2 (g)
Calculate the equilibrium constant for the reaction.
6. Hydrogen and carbon dioxide react at high temperatures to give carbon monoxide and
water vapor in the following reaction: H2 (g) + CO2 (g) CO (g) + H2O (g)
At equilibrium the concentrations of the components were found to be as follows [H2] =
0.105 M, [CO2]= 0.115, [CO ]= 0.916, and [H2O ] = 0.950. Calculate the equilibrium
constant at this temperature.
7. Sulfur trioxide and sulfur dioxide are in equilibrium according to the following
2 SO3 (g) 2 SO2 (g) + O2 (g)
Suppose that 3.00 moles of pure SO3 are placed in a 1.00 dm3 flask at 1150 K and
allowed to come to equilibrium. At equilibrium 0.58 mole of O2 was present. Calculate
the equilibrium constant for this system at 1150 K
8. The formation of nitrogen monoxide in a car engine at 2000 oC occurs as follows :
N2 (g) + O2 (g)
2 NO (g)
The value of kc for this reaction 5.0 x 10-2 at 200 0 oC . It 4.0 mole of N2 and 1.0 moles of
O2 are placed in a sealed container and allowed to come to equilibrium, calculate the
equilibrium concentrations of [N2], [O2], and [NO]
9. The reaction
2 NO (g) + O2 (g) 2 NO2 (g)
has an equilibrium constant of 100 at 300 K. What are the concentrations of NO2,
NO, and O2 at equilibrium, when a mixture of 2.0 moles of NO and 1.0 mole of O2 are
placed in a 1.0 dm3 container and allowed to come to equilibrium?