Questions: Elemental analysis of an unknown mineral tells you that the mineral consists of 29.3% Al, 20.6% F, 15.3% Si, and 34.8% O. What is the empirical formula of this mineral?
Transcript text: 20. Elemental analysis of an unknown mineral tells you that the mineral consists of $29.3 \% \mathrm{Al}, 20.6 \%$ $\mathrm{F}, 15.3 \% \mathrm{Si}$, and $34.8 \% \mathrm{O}$. What is the empirical formula of this mineral?
Solution
Solution Steps
Step 1: Convert Percentages to Grams
Assume we have 100 grams of the mineral. This simplifies the percentages directly to grams:
Al: 29.3 grams
F: 20.6 grams
Si: 15.3 grams
O: 34.8 grams
Step 2: Convert Grams to Moles
Use the molar masses of each element to convert grams to moles:
Molar mass of Al: 26.98 g/mol
Molar mass of F: 18.998 g/mol
Molar mass of Si: 28.085 g/mol
Molar mass of O: 16.00 g/mol
Moles of Al=26.98 g/mol29.3 g=1.0858 mol
Moles of F=18.998 g/mol20.6 g=1.0843 mol
Moles of Si=28.085 g/mol15.3 g=0.5449 mol
Moles of O=16.00 g/mol34.8 g=2.175 mol
Step 3: Determine the Simplest Whole Number Ratio
Divide each mole value by the smallest number of moles calculated: