What are the oxidation numbers of the underlined elements in each of the following and how do you rationalize your result?
(a) `KI_(3)`
(b) `H_(2)S_(4)O_(6)`
(c)`Fe_(3)O_(4)`
(d) `CH_(3)CH_(2)OH`
(e)`CH_(3)COOH`

Explanation

(a) `KI_(3) rarr +1 + 3(x) = 0`
`:.` x = -`1//3`
(b) `H_(2)S_(4)O_(6) rarr 2(+1) + 4(x) +6(-2) = 0`
`rarr ` 4x – 10 = 0 `rarr x = 10//4`
(c) `Fe_(3)O_(4) rarr 3(x) + 4(-2) = 0 `
`:. ` x = `+8//3`
(d)`CH_(3)CH_(2)OH rarr 2x + 6(+1) + 1(-2) =0 `
`rarr` 2x + 4 = 0 `rarr` 2x = -4
So, sum of O.S. of both carbon atoms is –4.
Oxidation number of c – 1 = -3
Oxidation number of c – 2 = - 1
(e) `CH_(3)COOH rarr 2x +4 – 4 = 0 `
`2x = 0 ` `rarr` x = 0
So, sum of oxidation states of both carbon atoms is zero.
Oxidation number of c – 1 = -3
Oxidation number of c – 2 = +3