A level Chemistry PAG- Help

1.3- Determination of the formula for magnesium oxide

Hi guys,

So the question is to find the amount in moles of Mg and O atoms in magnesium oxide that you prepared. then the empirical formula.

Idk where I went wrong but it does not equal to a 1:1 ratio, I'm stuck on the empirical formula bit (the question mark) IMG_7344 2.jpeg

(edited 2 years ago)

IMG_7344 2.jpg514.3KB

Reply 1

TriplexA

Original post by GiorgiosROu

Your workings seem fine to me. I think the answer is just Mg5O2

Reply 2

Trumbles

Are these the results of an actual experiment? I wonder whether some of the magnesium was left unreacted.

I realise that you want to get to a formula of MgO, but from the start it looks like the amount of mass of magnesium is too great compared to the mass of oxygen. It isn't that an error in your calculations has created that problem. (Strictly speaking the Oxygen should be 0.0025/0.0025 but obviously the answer is still '1'.)

So I think going for a formula like Mg₅O₂ is probably the best you can do now and hope for the mark on an error carried forward basis.
You could add "I was expecting a formula of MgO – possibly some of the magnesium remained unreacted."