This video explains how oxidation number of Sulphur in H2SO5 can be calculated from its structure. Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs to more electronegative atom.
It helps to identify whether the atom is in oxidised or reduced form.
Rules for calculating oxidation number
1.In free state oxidation number of an element is zero. Example Oxidation number of H2 is 0
2.The algebraic sum of the oxidation number of all the atoms in a compound must be zero
3. For monoatomic ions, oxidation number is equal to the charge on the ion, Example: For Fe3+, oxidation number is +3
4. For Polyatomic ion, the algebraic sum of oxidation number of atoms of the ions must equal the charge on the ion Example: CO32- ion, oxidation number is -2
5. For alkali metals, oxidation number is +1
6. Hydrogen : Oxidation number of hydrogen is +1
Exception: Binary compounds with metals, its oxidation number is -1
7.Oxygen: In most of the compounds oxidation number of oxygen is -2
Exception: In peroxide it is -1 & superoxide, it is -1/2.
If we analyze the structure of H2SO5, we can see there is a per oxy linkage between 2 oxygen atoms.
Hence oxidation number of Sulphur in H2SO5 is + 6.
