Chemical equilibrium: Kc , Kp

Kc
1. Write equation

• state
• reversible arrow

2. Initial amount/concentration

• use mol or M according to the question
• normally product is 0 except
• it duels with changes after reaching equilibrium

3. Equilibrium amount/concentration

• let the amt/conc. used be x (doesnt matter as long as 2 use the same unit)
  
• beware of the coefficient in front of x in the equation
• left - , right+ expect duels with changes after reaching equilibrium

4. Kc=
([pdt conc.]^coefficient x [pdt conc.]^coefficient......)
------------------------------------------
([react conc.]^coefficient x [react conc.]^coeffiecient......)

• If (2) use mole, divide mole by volume to get conc. here
• Unit= M^(pdt coeffiicient+pdt coefficient-react coefficient)

5. Equilibrium concentration

• substitute x
  

Kp
Principle:
Use mole fraction x total pressure to obtain partial pressure.
Partial pressure will understudy [pdt conc.] e.t.c.

Method
Add 'total mole' to step (2) and (3)
Add one step more after (3) for 'mole fraction'

*mole fraction = proportion of the gas inside(x100% becomes %)

Note:

1. Increase in volume = decrease in concentration. (if both sides of the equation has same volume, e.g. H2 + I2 <----> 2HI, then no change in position of equilibrium, otherwise change.)
   
2. Adding inert gas to increase the total pressure(V is constant) as no effect on the position of equilibrium since there is no change in concentration.
   
3. When product is gas but reactant is solid/liquid, Kp =product x product and no division.