Page 67 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

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

pH Calculations

pH of acids and bases in acid base reactions

+
1) pH of a Strong Acid pH = - log[H ]

-
2) pH of a Strong Base pOH = - log[OH ] and pH = 14 - pOH

pH = ½ (pK + pC )
3) pH of a Weak Acid a a
{C is the molar concentration of the acid}
a
pOH = ½ (pK + pC ) and pH = 14 - pOH
4) pH of a Weak Base b b
{C is the molar concentration of the base}
b

pH of salts is acid base reactions

1) Salt of a Strong Acid and pH = 7 e.g. NaCl, K SO
a Strong Base 2 4

pH < 7 e.g. NH Cl
2) Salt of a Strong Acid and a 4
Weak Base

3) Salt of a Weak Acid and a pH > 7 e.g. CH COONa
3
Strong Base

4) Salt of a Weak Acid and a It depends on the pK of the acid and pK of the base
a
b
Weak Base

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