why the melting point of magnessium oxide is higher than that of barium oxide?why here fajan's rule is not followed

Asked by Ankana Paul | 31st Oct, 2010, 11:10: AM

Expert Answer:

According to the Fajan's rule, barium oxide should have high M.P as compared to the magnesium oxide as barium oxide is more ionic than magnesium oxide.
But high ionic character doesn't means that every compound has high M.P, important factor to determine the M.P of any compound is the crystal structure (i.e. packing of the compound in crystal structure ).Proper packing means high M.P and in the case MgO,MgO has good packing in comparison of BaO and that's why it has high MP.

Answered by  | 1st Nov, 2010, 05:05: PM

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