Question

Part A

Phosgene (carbonyl chloride), COCl2, is an extremely toxic gas that is used in manufacturing certain dyes and plastics. Phosgene can be produced by reacting carbon monoxide and chlorine gas at high temperatures:

CO(g)+Cl2(g)?COCl2(g)

Carbon monoxide and chlorine gas are allowed to react in a sealed vessel at 462?C . At equilibrium, the concentrations were measured and the following results obtained:

Gas	Partial Pressure (atm)
CO	0.900
Cl2	1.30
COCl2	0.210

What is the equilibrium constant, Kp, of this reaction?

Part B

The following reaction was performed in a sealed vessel at 725?C :

H2(g)+I2(g)?2HI(g)

Initially, only H2 and I2 were present at concentrations of [H2]=3.80M and [I2]=3.00M. The equilibrium concentration of I2 is 0.0500M . What is the equilibrium constant, Kc, for the reaction at this temperature?

Answer 1

1)Kp=P[CoCl]/P[CO]P[Cl2]
Kp=0.21/(0.9x1.3)
Kp=0.21/1.17
Kp=0.179

2)

Make the "ICE" chart: I stands for initial concentration or pressure, C for change in conc./press. and E for equilibrium state

H2 + I2 <==> 2HI
I :: 3.6M 2.15M 0
(Since it is not mentioned in question, it will be 0)
C:: -X -X +2X
( here, since there are more reactants than product, the change in concentration is -X; coeff. goes in front of the X if there is one like the 2HI its +2X)
E:: 3.6 - X 2.15- X = .05 0+2(x)

to find X; 2.15 - .05 = X therefore, X = 2.1

now after you plug back in, you will get
1.5 for H2
4.2 for 2HI
and as given, .05 for I2

Now for Kc : (Product) raised to power of coeff. divided by Reactant raised to each of its coeff.
= (4.2)^2 divided by (1.5)^1 * (.05)^1
= Kc = 235.2 <---