Predicting the direction of approach to equilibrium:
At 448C the equilibrium constant kc for the reaction H
2
(g) + I
2
(g) 2HI(g) is
50.5. Predict in which direction the reaction proceeds to reach equilibrium if we start with 2.0x10
-2 mol of HI, 1.0x10
-2 mol of H
2 container.
and 3.0x10
-2 mol I
2 in a 2.00L
-compare K to Q

Predicting the direction of approach to equilibrium:
At 1000K the value of kp for the reaction 2SO
3
(g) 2SO
2
(g) + O
2
(g) is 0.338.
Calculate the value for Q p
P
SO2
= 0.41atm, P
O2 and predict the direction in which the reaction proceeds toward equilibrium if the initial partial pressures are P
SO3
= 2.5atm
= 0.16atm,

After a mixture of hydrogen and nitrogen gases in a reaction vessel is allowed to attain equilibrium at 427C, it is found to contain 7.38 atm H
2
, 2.46atm N
2 for the reaction N
2
(g) +
3
H2(g) 2NH
3 and 0.166atm
NH
3
. From these data, calculate the equilibrium constant k p

An aqueous solution of acetic acid is found to have the following equilibrium concentrations at 25C: [CH
3
COOH] = 1.65x10
-2 M, [H + ] = 5.44x10
-4 M,
[CH
3
COO ] = 5.44x10
-4 M. Calculate the equilibrium constant k c for the ionization of acetic acid at 25C.
CH
3
COOH(aq) H + (aq) + CH
3
COO (aq)

Calculating k Using Initial & Equilibrium
Concentrations
A closed system initially containing 1.000x10
-3 M H
2 and 2.000x10
-3 M I
2 at 448C is allowed to reach equilibrium and at the equilibrium the HI concentration is
1.87x10
-3 M. Calculate k c at 448C

For the Haber process, k p
=1.45x10
-5 at 500C. In an equilibrium mixture of the
3 gases at 500C, the partial pressure of H
2 is 0.928atm and that of N
2
0.432atm. What is the partial pressure of NH
3 is in this equilibrium mixture?
-would you use an ICE chart in this situation? why or why not?

At 500K the reaction PCl
5
(g) PCl
3
(g) + Cl
2
(g) has k p
= 0.497. In an equilibrium mixture at 500k, the partial pressure of PCl
5
PCl
3 is 0.350atm. What is the partial pressure of Cl
2 is 0.860 atm and that of in the equilibrium mixture?

A 1.000L flask is filled with 1.000mol of H
2
(g) and 2.000mol of I
2
(g) at 448C.
The value of the equilibrium constant K c for the reaction is 50.5. What are the equilibrium concentrations of H
2
, I
2
, and HI in moles per liter?
H
2
(g) + I
2
(g) 2HI(g)

For the equilibrium PCl
5
(g) PCl
3
(g) + Cl
2
(g), the equilibrium constant k p is
0.497 at 500K. A gas cylinder at 500K is charged with PCl
5
(g) at an initial pressure of 1.66atm. What are the equilibrium pressures of PCl
5
, PCl
3
, and Cl
2 at this temperature?

I Hate Quadratic Equations!!!!
Do you really have to use it?
Maybe not!
-if the subtraction of x would cause less than a 5% change in the concentration, then it can be ignored!
-Easy way to tell: divide the concentration given in the problem by the given k. If the answer is greater than
100, then x can be ignored

Given kc = 2.06x10
-9 at 25C. What is the equilibrium concentration of H+ if the initial concentration of HOBr is 1.25M. HOBr(aq) OBr (aq) + H + (aq)

As if there weren’t enough k’s… k sp
= solubility product constant
-refers to solids dissolving in aqueous solution
Given: Cu(IO
3
)
2 dissolves in water to form Cu is the concentration of Cu 2+ at equilibrium?
2+ and 2IO 3. If k sp
= 1.4x10
-7 what