Ionic equilibrium


Ionic equilibrium

1.
 Degree of dissociation or ionization  = 

For strong electrolytes   1, for weak electrolyte  < < 1

2. Ostwald's dilution law  For a weak electrolyte of type A+ B-

dissociation constant, k = 

or  = 

Where C = Concentration

            K – Dissociation constant

            V = Volume


3. For weak monobasic acids  = 

for weak non acidic bases  = 

Ka = dissociation constant of weak acid

            Kb = dissociation constant of weak base



4. Relative strength of two acids



5. Ionic product of water, Kw = or = 10-14 at 25°C

6. pH = 

pKw = pH + pOH = 14 at 25°C

and pKa + pKb = 14

where pKa = - log Ka and pKb = - log Kb

7. If the solubility of a salt like A2B3 is S mol L-1, then



Solubility product Ksp = (2s)2 (3s)3

= 108 s5

8. pH of an acidic buffer is given by Henderson equation

pH = pKa + log

pH of a basic buffer is given by

pOH = pKb + log 

and then pH = 14 - pOH.

9. Buffer capacity = 

or  = 

10. For salts of weak acid and strong base hydrolysis constant, Kh = 

Degree of hydrolysis h = 

pH = 

11. For salts of strong acid and weak base

Kh = 

H = 

pH = 

12. For salts of weak acid and weak base

hydrolysis constant Kh = 

pH = 

13. In case of salt of weak acid and weak base, nature of medium hydrolysis is decided as :

(i) If Ka = Kb (medium will be neutral)

(ii) If Ka > Kb (medium will be acidic)

(iii) If Ka < Kb, (medium will be basic)



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