Answer:
[CO] = 0.62 M
Explanation:
Step 1: Data given
Volume of the flask = 500 mL
Number of moles CO = 1.0 moles
Number of moles H2O = 1.5 moles
Number of moles CO2 = 0.70 moles
The equilibrium constant K for this reaction is 3.80
Step 2: The balanced equation
CO(g) + H2O(g) ⇆ CO2(g) +H2(g)
Step 3: Calculate the initial concentrations
Concentration = moles / volume
[CO] = 1.0 moles / 0.500 L = 2.0 M
[H2O] = 1.5 moles / 0.500 L = 3.0 M
[CO2] = 0.70 moles / 0.500 L = 1.4 M
[H2] = 0M
Step 4: The concentration at the equilibrium
For 1 mol CO we have 1 mol H2O to produce 1 mol CO2 and 1 mol H2
[CO] = 2.0 -X M
[H2O] = 3.0 - X M
[CO2] =1.4 + X M
[H2] = X M
Step 5: Define Kc
Kc = [CO2][H2]/ [CO][H2O]
3.80 = (1.4 + X) * X / ((2.0 - X)*3.0 -X))
X = 1.38
[CO] = 2.0 -1.38 = 0.62 M
[H2O] = 3.0 - 1.38 = 1.62 M
[CO2] =1.4 + 1.38 M = 2.78
[H2] = 1.38 M
Kc = (2.78*1.38) / (0.62*1.62)
Kc = 3.8
[CO] = 0.62 M
