M0.98 O1.00 is non-stoichiometric compound and is a mixture of M2+ and M3+ ions.
Let x atoms of M3+ are present in the compound. This means that x M2+ have been replaced by M3+ ions.
∴ Number of M2+ ions = 0.96 – x.
For electrical neutrality, positive charge on compound
= negative charge on compound.
∴ 2(0.96 – x) + 3x = 2
1.92 – 2x + 3x = 2
or x = 2 – 1.92 = 0.08
Thus, M2+ is 92% and M3+ is 8% in given sample having formula, M0.96 O1.00.
The number of tetrahedral voids formed is equal
to twice the number of atoms of element N and only of these are occupied by the element M. Hence the ratio of number of atoms of M and is So, the formula of the compound is M2N3.