how many grams of Fe2O3 are formed when 16.7g of Fe reacts completely with oxygen.

4Fe +3O2 --> 2Fe2O3

how do i do this problem..thanks:)

2 answers

(a) Look up the molar mass of Fe (= the atomic mass of Fe labeled "gFe/mol")
(b) Divide16.7gFe by (a) to get moles of Fe
(c) Multiply (b) by 2molFe2O3/4molFe (or 2/4) to get moles of Fe2O3 produced.
(d) multiply (c) by the formula mass of Fe2O3*

*To find the formula mass of Fe2O3, look up each atomic mass, multiply each by the subscript, and add add them all up.
If you do that you get the wrong answer