Javier forgot to polish the magnesium metal. Will the reported mole ratio of magnesium to oxygen be too high or too low as a result of his mistake? Explain.

Question

festinger · Answer

DAMMIT JAVIER, POLISH YOUR MAGNESIUM!

I predict that it will be lower, though I have no idea what context this is in.
I imagine this would be done in a experiment where a magnesium ribbon is burnt. So he will be measuring the mass of the Magnesium before the experiment, and then use that mass to obtain the number of mols of magnesium atoms. Due to the prescence of MgO, the mass is actually heavier, so the number of calculated mols is higher.

After burning, the mass is measured again, and then the difference in mass is noted, and then divided by 16(Ar, Oxygen) to finally to find the ratio. Thing is, there is more magnesium that we calculated,  the end result will be that the calculated ratio is lower.

$$\frac{mol of O_{2}}{mol of Mg}=ratio$$

-because a bigger denominator will give a smaller result-