Page 44 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

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

3) Redox reactions

❖ A reaction where one or more electrons are transferred from one atom to another.

✓ Oxidation is loss of electrons

✓ Reduction is gain of electrons

❖ Oxidation and reduction always occur simultaneously.

▪ The ion that gains electrons is said to be reduced, it is an oxidizing agent.
- +2
e.g. MnO + 5e → Mn (+7 → +2)
4
▪ The ion that loses electrons is said to be oxidized, it is a reducing agent.
+2 +3
e.g. Fe → Fe + e (+2 → +3)
➢ The driving force of the reaction is the movement of electrons according to the

potential gradient.

4) Complexation reactions

❖ Complex ions are formed by the combination of one ion (metal ion) with one or
more ions or molecules (ligand) by one or more coordination bonds.
y
❖ Generally; M x+ + nL ↔ [MLn] x+ny
L: ligand (contains lone pair of free electrons), n: coordination number

➢ The driving force in all the above reactions is the formation of complex ion.
➢ Examples:
2-
-
2+
Pb + 4 Cl ↔ PbCl4
+
-
-
Ag + 2CN ↔ [Ag(CN)2]
2+
Cu + 4NH3 ↔ [Cu(NH3)4] 2+
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