Empirical Formulas Part 2
1. A compound contains 40.0% Carbon, 6.73% Hydrogen, and 53.3% Oxygen. Find:
a. Empirical Formula
b. Empirical Mass
c. Molecular Formula, if the Molecular mass is 181 g.
2. If a compound is 85.70% Carbon, 14.30% Hydrogen, and the molecular mass is 56,
find:
a. Empirical Formula
b. Molecular Formula
3. A sample of “red lead,” a compound used to prevent the corrosion of steel, has a mass
of 4.997 g. Of this, 0.4670 g is Oxygen, the rest lead. Determine:
a. Percent O
b. Percent Pb
c. Empirical Formula
4. Nicotine is a compound that contains 74% Carbon, 17.33% Nitrogen, and 8.67%
Hydrogen. Find the empirical formula of nicotine.
5. Copper Sulfate is frequently found as a bluish compound, containing water. If you
heated a sample of hydrated (meaning water-attached) Copper Sulfate that had a mass
of 2.576 g, and drove off all the water, leaving you with copper sulfate, the resulting
compound had a mass of 1.646 g. Find:
a. The mass of the water your drove off.
b. The empirical formula of the hydrated salt.
*--Hydrated Copper sulfate will have a formula that looks like this: CuSO4 (XH2O)
where “X” is the number of water molecules attached.
6. Elemental analysis reveals that a certain compound is made up of 26.57% K, 35.36 %
Cr, and 38.07 % O. Find the empirical formula.
7. A 1.600 g sample of Chromium- Oxygen compound contains 1.095 g of Chromium.
Determine the empirical formula.
8. A compound consists of 19.30 % Na, 26.91 % S, and 53.80 % O. Find:
a. The empirical formula
b. The molecular formula, if the molecular mass is 237.9 g.
9. A compound contain 20.11 % H, and 79.89% C. Find:
a. The empirical formula
b. The molecular formula, if the molecular mass is 30 g.