Name: _______________________
SCH3UI
Date:____________________
Empirical and Molecular Formula Calculations
1. Butane has an empirical formula of C2H5. Butane is a fuel that is found in disposable
lighters. A mass spectrometer was used to determine the molar mass of butane. It
was discovered to be 58.00 g/mol. What is the molecular formula of butane? (C4H10)
2. Oxalic acid, is found in rhubarb leaves. It has an empirical formula of CHO2. Its molar
mass is 90.00 g/mol. What is the molecular formula of oxalic acid? (C2H2O4)
3. Codeine, a pharmaceutical used for pain relief has an empirical formula of C 18H21NO3.
What is the molecular formula of codeine if the molar mass is 299.00 g/mol
(C18H21NO3).
4. An unknown compound was discovered to have a molar mass of 240.28 g/mol. The
percentage composition by mass consists of 75.0% carbon, 5.05% hydrogen, 20.0%
oxygen. What is the compound’s molecular formula? (C15H12O3).
5. The common name for tartaric acid is cream of tartar. Cream of tartar is used in
baking. It has an empirical formula of C2H3O3. If 1.00 mole of tartaric acid contains
3.61 x 1024 oxygen atoms, what is the molecular formula of tartaric acid? (C4H6O6)
6. Vinyl acetate, C4H6O2 is a chemical monomer used to make polymers in products like
computer discs, and plastic film.
a. What is the empirical formula of vinyl acetate? (C2H3O)
b. How does the molar mass of vinyl acetate compare to the molar mass of the
empirical formula? (double)
7. An unknown compound has a molar mass of 186 g/mol. The compound has a formula
of C6xH5xOx, where x is a whole number. Determine the compound’s molecular
formula? (C12H10O2).
8. What is the percentage by mass of water in magnesium sulfite hexahydrate? (50.88%)
9. A 3.34 g sample of a hydrate has the formula of SrS2O3●xH2O, contains 2.30 g of
SrS2O3. Find the value of x. (x = 5, SrS2O3●5H2O)
10. A hydrate of zinc chlorate, Zn(ClO3)2 ●xH2O, contains 21.5% zinc by mass. Find the
value of x. (x = 4, Zn(ClO3)2 ●4H2O)