The valency of sulphur in SO2 and SO3 is 4,6. Pls explain how?

_{2}and SO

_{3}are:

1) The sum of all oxidation numbers in a neutral compound is zero.

2) The oxidation number of oxygen in a compound is usually –2. If, however, the oxygen is in a class of compounds called peroxides (for example, hydrogen peroxide), then the oxygen has an oxidation number of –1. If the oxygen is bonded to fluorine, the number is +1.

Now in SO

_{2}

Let oxidation state of sulphur be 'x'

Oxidation state of oxygen = -2 {Using rule-2}

Total charge = 0 {Using rule-1}

The equation is: x + 2(-2) = 0

x - 4 = 0

x = 4

Therefore oxidation state of Sulphur in SO

_{2}is +4.

Now in SO

_{3}

Let oxidation state of sulphur be 'y'

Oxidation state of oxygen = -2 {Using rule-2}

Total charge = 0 {Using rule-1}

The equation is: y + 3(-2) = 0

y - 6 = 0

y = 6

Therefore oxidation state of sulphur in SO

_{3 }is +6

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