Question

Calculate how many grams of Fe2O3 (molar mass 159.70 g/mol) are formed when 16.7 g of Fr react completely with O2.4 Fe + 3 O2—> 2 Fe2O3

Answer 1

The first step to solve this question is to convert the given amount of grams of Fe to moles using its molecular weight.

$16.7gFe\cdot\frac{mol}{55.845gFe}=0.3molFe$

According to the given reaction, 4 moles of Fe produce 2 moles of Fe2O3. Use this ratio to find how many moles of Fe2O3 are formed:

$0.3molFe\cdot\frac{2molFe_2O_3}{4molFe}=0.15molFe_2O_3$

Convert this amount of moles to grams using Fe2O3 molar mass:

$0.15molFe_2O_3\cdot\frac{159.70g}{molFe_2O_3}=23.9g$

It means that 23.9 grams of Fe2O3 are formed.