Title: Determining an Empirical Formula
Objective: Using mass relationships,
show that magnesium and oxygen
combine in a definite whole number ratio
by mass.
Equipment:
Materials: 35 cm of magnesium ribbon
Procedure:
Data:
Mass of empty crucible ________g
Mass of crucible + Mg _________g
Mass of crucible + O __________g
Calculations:
1. Find the mass of Mg
2. Find the mass Of O
3.
4.
5.
Find the number of moles of Mg
Find the number of moles of O
Find the whole number ratio
Conclusions and Questions:
1. Write the empirical formula for magnesium oxide.
2. What was the ratio by mass of Mg used to the mass of O used? How does it
compare to the mole ratio?
3. The molecular mass of a compound is 75 grams and the empirical formula is CH3.
Calculate the molecular formula.
4. How is the chemical composition of carbon monoxide similar to that of carbon
dioxide? How is it different?
5. A sample of sulfur having a mass of 1.28 g combines with oxygen to forma
compound with a mass of 3.20 g. What is the empirical formula of the
compound?