[stars_below]

A 4.628-g sample of an iron oxide was found to contain 3.348 g of iron and 1.280 g of oxygen. What is the simplest formula for this compound?

i solved up to the point of having FeO_1.3 but i don't know what to do next, can anyone help

[Albert]

Certainly a chemical formula should contain integers only. I believe you solved the problem correctly: you simply forgot that, in this case, you always have to approximate to the closest integer (but perhaps it's not your fault: no one has ever told you it).

Hence, I bet the answer is just FeO.

[Borek]

Check if Fe₃O₄ doesn't fit better

[stars_below]

Fe₃O₄ is the answer that im suppose to get, but i don't know how to figure it out, am i suppose to do something with the 4.628g?

[enahs]

You have 0.059 mol of Iron and 0.040 mol of O.

That means you have

0.059 mol Fe
0.080 mol O

Or in English and doing the math that ratio means you have 1.35 mol of O per 1 mol of Fe.
You need whole numbers, so what is the smallest whole number you need to multiply by to get that 1.35 to be a integer? By 3, which 1.35 * 3 = 4.05 which is ~4. Now you must also be fair mathematically and multiply the Fe times 3 as well. After that is all done you have Fe₃O₄.