Honors Chemistry
Name____________________________
Molecular Formulas and Formulas for a Hydrate
1. Monosodium glutamate (MSG) is sometimes added to food to enhance flavor. Analysis determined
this compound to be 35.5% C, 4.77% H, 8.29% N, 13.6% Na, and 37.9% O. What is the empirical
formula for MSG?
2. The hydrocarbon used in the manufacture of foam plastics is styrene. Analysis of styrene indicates
the compound is 92.25% C and 7.75% H and has a molar mass of 104 g/mol. Determine the molecular
formula of styrene.
3. Determine the molecular formula for ibuprofen, a common headache remedy. Analysis of
ibuprofen yields a molar mass of 206 g/mol and a percent composition of 75.7% C, 8.80% H, and
15.5% O.
4. Vanillin is a common flavoring agent used in foods. This compound consists of 63.15% C, 5.30%
H, and 31.55% O. The molar mass is 152 g/mol. Determine both its empirical and molecular formula.
5. A particular compound in the chemistry lab is found to contain 7.2 x1024 atoms of oxygen, 56.0 g of
nitrogen, and 4.0 moles of hydrogen. What is its empirical formula?
6. The compound A2O is 63.7% A (a mystery element) and 36.3% oxygen. What is the identity of
element A?
7. Adipic acid is an organic compound composed of 49.31% C, 43.79% O, and the rest hydrogen. If
the molar mass of adipic acid is 146.1 g/mol, what are the empirical and molecular formulas for the
acid?
8. Hydrated sodium tetraborate (Na2B4O7  x H2O) is commonly called borax. Chemical analysis
indicates that this hydrate is 52.8% sodium tetraborate and 47.2% water. Determine the formula and
name the hydrate.
9. Gypsum is hydrated calcium sulfate. A 4.89 g sample of this hydrate was heated, and after the
water was driven off, 3.87 g anhydrous calcium sulfate remained. Determine the formula of this
hydrate and name of the compound.
10. The table below shows data from an experiment to determine the formula of hydrated barium
chloride. Determine the formula for the hydrate and its name.
Data for BaCl2  x H2O
Mass of empty crucible
Mass of hydrate and crucible
Initial mass of hydrate
Mass after heating 5 minutes
Mass of anhydrous solid BaCl2
21.30 g
31.35 g
29.87 g
Challenge Problem:
a) A given sample of a xenon fluoride compound contains molecules of the type XeFn, where n is
some whole number. Given that 9.03 x 1020 molecules of XeFn weigh 0.368 g, determine the
value for n in the formula and write the correct name of the compound.
b) Draw the Lewis dot diagram for the xenon fluoride compound for which you determined the
formula in part a.
c) What is the molecular geometry of the xenon fluoride compound? Is it polar or nonpolar?