the honors chemistry mole quiz practice

1. Explain why the mole is such an important concept in chemistry.
2. A) What is the mass in amu of a single carbon-12 atom? B) How many carbon-12
atoms are present in a mole of carbon-12? C) What is the mass (in grams) of a mole of
carbon-12 atoms?
Show your work for problems 3-11
3. What is the mass of 3.56 x 1024 formula units of iron (III) hydroxide?
4. How many mL of water would have the same number of representative particles as are
present in 80.0 grams of NaOH. (The density of water = 1g/mL)
5. A sample of calcium carbonate contains 10.4 grams of the element oxygen. What is
the mass of the entire sample of calcium carbonate?
6. How many atoms of oxygen are present in 2.50 moles of zinc perchlorate?
7. (A) Calculate the percent composition of lead and oxygen in lead (IV) sulfate.
(B) Then use this data to determine the number of grams of oxygen which could be
extracted from a 15.0 gram sample of lead (IV) sulfate.
8. Determine the empirical formula and molecular formula of caffeine, which is
composed of 49.5% carbon, 5.1 % hydrogen, 28.9% nitrogen, and 16.5% oxygen. The
formula mass of caffeine is 195 amu.
9. A common compound used to prepare hard water for washing laundry is a hydrate
called washing soda. It’s formula can be written Na2CO3xH2O. When a 6.395 gram
sample of washing soda is heated, all the water of hydration is lost, leaving 2.370 grams
of Na2CO3. Determine the value of “x” and then write the formula for washing soda.
10. Cumene is a compound containing only carbon and hydrogen that is used in the
production of acetone and phenol. Combustion of 47.6 mg of cumene produces 156.8 mg
of carbon dioxide and 42.8 mg of water. The molar mass of cumene 120.0 g/mol.
Determine the empirical formula and molecular formula of cumene.
11. (On your own paper -- Add #72 from the book, for combustion analysis with oxygen involved!)