Percent Composition and Empirical Formula Quiz

Percent Composition, Empirical, Molecular and

Hydrate Formulas Review

Calculate the percent composition of each element in the following compounds. SHOW ALL WORK ON NOTEBOOK PAPER!!

Determine the empirical formula for the following. (Hint: simplify)

3. C2H44. C4H8O2

Determine the formula for each of the following. Show all work on notebook paper.

5. The compound styrene has a composition that is 92.25% carbon and 7.75% hydrogen.

6. MSG (monosodium glutamate) a common food additive has a composition of 35.5% carbon,

4.77% hydrogen, 8.29% nitrogen, 13.6% sodium, and 37.9% oxygen.

7. Ricinine, a poisonous compound found in the castor plant, is composed of 58.4% carbon,

4.91% hydrogen, 17.06% nitrogen, and 19.49% oxygen. The molar mass of ricinine is 164.16

g/mol. Determine the molecular formula for ricinine.

8. Triethylenemelamine is used in the plastics industry and as an anticancer drug. Its analysis

is 52.93% carbon, 5.92 % hydrogen, 41.15% nitrogen. The molecular mass of

triethylenemelamine is 204.2 g/mol. What is its empirical formula? What is its molecular

formula?

9. Cobalt (II) nitrate hydrate is used in ceramic glazes and produces a blue color when fired.

If 34.5 g of the hydrate is heated until all that is left is 21.7 g anhydrous cobalt(II) nitrate.

What percentage of the compound is water? What is the molecular formula for the hydrate?

10. A 17.44 g sample of a hydrate of zinc sulfate is heated in a crucible to drive off all of the

water. After heating, the sample has a mass of 9.79g. What is the empirical formula for this

hydrate?