1. How many atoms of copper are present in .52 mole of pure copper? 2. What is the mass, in grams, of 1.23 mole of Silver (Ag)?

3. What is the mass, in grams, of 2.0110 x 1.021 glucose atoms (CsH1206)?

4. How many moles of Clare in .52 mole of CaCl2?

5. How many grams of O are in 33.20 g of Ca3(PO4)2?
6. Calculate the mass percent of O in 86 g of the compound Fe2O3

7.65% of elemental carbon with a mass of 24.6 g is found in the compound C5H10. What is the mass of the compound?
8. a 1.45 g sample of phosphorus buns in air and forms 2.57 g of phosphorus oxide. Calculate the empirical formula
9. calculate the empirical formula for the compound below:
Pineapple oil AKA Ethyl butyrate: C, 62.04%; H, 10.41%; 0, 27.55%
10. A compound containing carbon and hydrogen has a molar mass of 56.11 g/mol and an empirical form ula of CH2. Determine its molecular formula
11. Caffeine, a stimulant found in coffee and soda, has the mas percent composition; C, 49.48%; H, 5.19%; N, 28.85%; 0, 16.48%. The molar mass of caffeine is 194.19G/mol. Find the molecular formula of caffeine.

SELF-TEST QUESTIONS
A. Match the following terms with the phrases below.
empirical formula empirical formula molar mass mass percent (composition)
molar mass mole (mol) molecular formula
1. Quantity used by chemists with a value of 6.022 x 1023 2. Mass of one mole of atoms of an element or one mole of molecules or formula units of a
compound 3. An element's percentage of the total. mass of a compound 4. Formula that gives the specific number of each type of atom in a molecule 5. Formula that gives the smallest whole number ratio of each type of atom in a molecule 6. Sum of the masses of all the atoms in the enpirical formula
C. Multiple Choice
1. How many silver atoms are in the 0.40 mol Ag?
a) 2.4 x 1023 b) 6.0 x 1023 c) 1.5 x 1024 d) 2.4 x 1024
2. How many moles of gold atoms are in 1.63 x 1022 atoms of gold?
a) 0.0271 mol b) 4.39 mol c) 5.86 mol d) 36.9 mol
3. What is the mass, in grams, of 0.522 mol copper?
a) 0.522 g b) 33.2 g c) 63.6 g d) 3.14 x 1023 g
4. How many sugar molecules, C12H22011, are in 30.0 g of sugar?
a) 5.28 x 102 molecules b) 2.01 x 104 molecules c) 1.81 x 104 molecules d) 6.18 x 104 molecules
5. What is the mass, in grams, of 3.18 x 1021 formula units of Ca3(PO4) 2?
a) 0.882 g b) 1.31 g c) 1.47 g d) 1.64 g
6. How many moles of H are in 0.424 mol Ca(C2H2O2)2?
a) 0.848 mol H b) 1.27 mol H c) 2.12 mol H d) 2.54 mol H
Chapter 6
7. Calculate the mass percent S in Na2S2O3.
a) 20.28% b) 31.13% c) 40.56% d) 45.13%
8. A compound consists of 25.94% N and 74.06% O by mass. Determine the empirical formula
of the compound. a) NO b) NO3 c) N204 d) N2O5
9. A compound is formed by the combination of 13.99 g iron with 6.01 g oxygen. What is the
empirical formula of the compound? a) Feb b) Fe2O c) FeO2 d) Fe2O3
10. A compound has an empirical formula of CH2 and a molar mass of 84.18 g/mol. Find its
molecular formula.
a) C4H8 b) CsH10 c) C6H12 d) C7H14