Question

How many grams of magnesium oxide can be produced when 97.2 g Mg react with 88.5 g O2?

Answer 1

i would balance the equation, then do a limiting reagent problem.

Answer 2

You can either reason with masses and proportionality as rs32623 does, or convert masses of Mg and O2 to amounts in moles, then solve your problem.

Either way, you should find around 160 g of MgO (there is a small mistake in the value given above).

Answer 3

Our equation is 2Mg + O2=2MgO also 4Mg + 2O2=4MgO
Atomic mass of Mg is 24.3 & Molecular mass of O2 is 32 which means as per the balanced equation we require 48.6 gram of mg for every 32 gram of oxygen which gives us 2*(24.3+16) gram of MgO & for 97.2 gram of Mg we require 64 gram of oxygen which will give us 4*(24.3+16) ie. 161.2 gram of MgO.
Clearly oxygen in excess & Mg is a limiting reagent.
Thus we have 161..2 gram of MgO formed.