A sample of ferrous oxide has actual formula Fe0.93O1.00. In this sample what fraction of metal ions are Fe2+ ions? What type of nonstoichiometric defect is present in this sample?

For 1→ O there is 0.93 Fe


Let 100→ O2- is present in sample. To maintain neutrality Fe2+ and Fe3+ should be present in such a ratio that it counterbalances the negative charge.


Let number of Fe2+ be X


number of Fe3+ be 93-X


since total positive charge must be equal to total negative charge as compound is overall neutral,


2X+3(93-X)=2× 100


2X+279-3X=200


X=79


Fe2+ =79


Fe3+ =93-79=14


Fraction of Fe2+ is = 0.849.


This is metal deficiency defect as iron present in sample is in less amount than required for stoichiometric composition.


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