[abhar]

I am doing a lab on the combustion of magnesium.  We heated magnesium in a crucible over a bunsen burner until it became MgO.  We know the actual chemical formmula was MgO, but our mass measurements eventually gave us the formula Mg2O, but our teacher said it was ok.  

There is a question that says:
Suppose that you had allowed some magnesium oxide smoke to escape during the investigation.  How would the Mg:O ratio have been affected?  Would the ratio increase decrease or remain unchanged.  Explain using sample calculations.  

I don't understand??  If it is magnesium oxide gas that it escaping, why would the ratio change?  Am I correct?

[kevins]

When Mg burn in air, both MgO and Mg2N3 are form. Therfore if you count all the final products are MgO, then the ratio should have a little bit different.

[Tetrahedrite]

If you did the experiment on a humid day there is a strong chance that brucite-Mg(OH)2 was formed as well, which could explain the ratio