Analysis shows 2.431g of magnesiumm, Mg chemically combined with ecxactly 1.6g oxygen O2, to form an oxide?
Answer:
2.431/ 24.3g/mol= .1mol Mg
1.6g/ 31.9998g/mol = .05 mol O2
0.1/0.05=2
so 2 Mg per 1 O2
or just MgO
Divide the 2.341 by the accurate Ar of Mg, and you will get 0.100 moles of Mg.
Do the same with 1.6g of O2, and you will get 0.0500 moles of O2 molecules, which is 0.100 moles of O atoms.
The formula is therefore MgO.
x = y = 1.
The important piece of information here is the relative number of moles you have of these chemicals, because atoms combine based on mole ratios, not mass ratios. Okay, so from a periodic table, you can see that Mg weighs 24.31 g/mol. That means that you have 2.431g / 24.31 g/mol = 0.10 moles of magnesium. Oxygen weighs 16.00 g/mol, so you have 1.6g / 16.00 g/mol = 0.10 moles of oxygen. So you've got 0.10 moles of each, and therefore a 1:1 ratio. So the formula is simply MgO (magnesium oxide), where both of your subscripts are "1". When it's a "1", you don't write anything in the subscript - it's just assumed to be a "1".
Good luck!
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