Practice with Conversions, Formula Masses, Molar Masses, Empirical Formula, and Molecular

Name ______Date ______

Practice with conversions, formula masses, molar masses, empirical formula, and molecular formula.

1. Calculate the number of moles in each of the following masses: 2 a. 7.50 X 10 g of methanol, CH3OH

b. 50.0 g of calcium chlorate

2. Determine the mass of each of the following amounts: a. 0.120 mol of glucose, C6H12O6

b. 6.94 mol barium chloride

3. Calculate the number of molecules in 4.99 mol of methane, CH4 .

4. Calculate the mass of 8.25 X 1022 molecules of bromine pentafluoride.

5. Write formulas for the following compounds and determine the percentage composition of each: a. mercury(II) sulfate b. antimony(V) fluoride 6. Calculate the percentage of the given element in each of the following compounds: a. sulfur in sulfuryl chloride, SO2Cl2

b. oxygen in potassium chlorate, KClO3

7. Calculate the mass of oxygen in 4.00 g of manganese dioxide, MnO2

8. Determine the empirical formula for compounds that have the following analyses: a. 66.0% barium and 34.0% chlorine

b. 80.38% bismuth, 18.46% oxygen, and 1.16% hydrogen

c. 12.67% aluminum, 19.73% nitrogen, and 67.60% oxygen

2 9. Sometimes, instead of percentage composition, you will have the composition of a sample by mass. Use the actual mass of the sample instead of assuming a 100 g sample. Determine the empirical formula for compounds that have the following analyses: a. a 0.858 g sample of an unknown substance is composed of 0.537 g of copper and 0.321 g of fluorine

b. a 13.07 g sample of an unknown substance is composed of 9.48 g of barium, 1.66 g of carbon, and 1.93 g of nitrogen

10. Determine the molecular formulas for compounds having the following empirical formulas and molar masses: a. C2H4S; experimental molar mass 179

b. C2H4O; experimental molar mass 176

3 11. Use the experimental molar mass to determine the molecular formula for compounds having the following analyses: a. 41.39% carbon, 3.47% hydrogen, and 55.14% oxygen; experimental molar mass 116.07

b. 54.53% carbon, 9.15% hydrogen, and 36.32% oxygen; experimental molar mass 88