Question

A brown substance contained 10.87 grams of Iron and 4.66 grams of Oxygen.What is the emperical formula?

Answer 1

Answer:  $Fe_2O_3$

Explanation:

Mass of Fe = 10.87 g

Mass of O = 4.66 g

Step 1 : convert given masses into moles.

Moles of Fe =$\frac{\text{ given mass of Fe}}{\text{ molar mass of Fe}}= \frac{10.87g}{56g/mole}=0.19moles$

Moles of O =$\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{4.66g}{16g/mole}=0.29moles/tex]</p><p>Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated</p><p>For Fe = [tex]\frac{0.19}{0.19}=1$

For O =$\frac{0.29}{0.19}=1.5$

The ratio of Fe: O = 1 : 1.5

Converting them into whole number ratios : Fe :O = 2: 3

Hence the empirical formula is $Fe_2O_3$