Question

Calculate oxidation number of the following compounds :
(i) Fe in FeSO₄
(ii) Fe in Fe(CO)₅
(iii) P in H₃PO₃
(iv) S in H₂S₂O₇
(v) C in C₁₂H₂₂O₁₁
(vi) P in NaH₂PO₂

Answer 1

(i) Suppose oxidation number of Fe in FeSO₄ = x
x + 1(-2) = 0
x – 2 = 0
x = +2
∴ Oxidation number of Fe FeSO₄ = +2

(ii) Suppose, oxidation number of Fe in Fe(CO)₅ = x
x + 5(0) = 0
x + 0 = 0
x = 0
∴ Oxidation number of Fe Fe(CO)₅ = 0

(iii) Suppose, oxidation number of P in H₃PO₃ = x
3(+1) + x + 3(-2) = 0
3 + x – 6 = 0
x – 3 = 0
x = +3
∴ Oxidation number of P in H₃PO₃ = +3

(iv) Suppose, oxidation number of S in H₂S₂O₇ = x
2(+1) + 2x + 7(-2) = 0
2 + 2x – 14 = 0
2x – 12 = 0
2x = 12
x= \(\frac{12}{2}\) = 6
∴ Oxidation number of S in H₂S₂O₇ = +6

(v) Suppose, oxidation number of C in C₁₂H₂₂O₁₁ = x
12x + 22(+1) + 11(-2) = 0
12x + 22 – 22 = 0
12x + 0 = 0
12x = 0
x = 0
∴ Oxidation number of C in C₁₂H₂₂O₁₁ = 0

(vi) Suppose, oxidation number of C in P in NaH₂PO₂ = x
1(+1) + 2(+1) + x + 2(-2) = 0
1 + 2 + x – 4 = 0
x – 1 = 0
x = +1
∴ Oxidation number of C in P in NaH₂PO₂ = +1