1. Top 10 things you should know about K:
It’s such a great letter, all famous people have K as a 1st or 2nd initial!
Determined by the law of mass action
Units can be variable…depends on the reaction; therefore not shown.
Stays the same even though equilibrium position can change.
Sometimes Kc=Kp
Does not vary as the amount of solids and liquids change in reactions
Can be compared to Q
If it’s big, watch out…many products!
If it’s small, beware…many reactants!
Sometimes calculations involve the quadratic formula!

2. 3 Scenarios for solving problems revolving around K
Given K and enough equilibrium concentrations other equilibrium concentrations can be found.
Given starting concentrations and one equilibrium concentration, K can be found.
Knowing initial conditions and K (using Q and stoichiometry) equilibrium concentrations can be found.

3. Given the system: COCl2(g) ↔ CO(g) + Cl2(g)
With a Kp value of 6.8 x 10-9 (at 100.0°C), what would the eq. concentrations of all species be if 4.25 atm of phosgene was placed into a container at 100.0°C and the system is allowed to come to equilibrium?
0.139 M = [COCl]
M = [CO]
M = [Cl2]

4. H2S(aq) ↔ H+(aq) + HS-(aq)
Given the system:
H2S(aq) ↔ H+(aq) HS-(aq)
With a Keq value of 1.0 x 10-7 (at 25.0°C), what would the eq. concentrations of all species be if 1.5 moles of hydrogen sulfide was placed in enough water to make mL of solution at room temperature and the system is allowed to come to equilibrium?
3.0 M = [H2S]
M = [H+]
M = [HS-]