Page 66 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

For pure water at room temperature (25°C):

-
+
[H ][OH ] was experimentally found to be 1 x 10 M, pKw = pH + pOH = 14
-14
Relation between:
pK of an acid and pK of its conjugate base
a b
pK + pK = pK = 14
a b w
- +
e.g. CH COOH ⇌ CH COO + H pK + pK = 14
3 3 a (acetic acid) b (acetate)
pK of a base and pK of its conjugate acid
b a
pK + pK = pK = 14
b a w
+ -
e.g. NH OH ⇌ NH + OH pK + pK = 14
4 4 b (amm hydroxide) a (ammonium)
Note that: small “p” means “-log”

“[ ]” means “molar concentration

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