1. CHAPTER 7
Gameday Review

2. MOLE CONVERSIONS
Determine the number of atoms present in mol of sodium
9.33 x 1023 atoms Na

3. MOLE CONVERSIONS Determine the mass in grams of 0.750 mol of francium.
167 g Fr

4. MOLE CONVERSIONS
A sample of lead has a mass of g. How many atoms does the sample contain?
4.360 x 1023 atoms Pb

5. MOLE CONVERSIONS
Convert 2.65 x 1025 atoms of fluorine to grams of fluorine.
8.36 x 102 g F

6. MOLAR MASS
Calculate the molar mass of phenol (C6H5OH)
94.12 g / mol

7. Molar Mass
Sodium Sulfate
Na2SO4 = g/mol

8. AVERAGE ATOMIC MASS
Calculate the average atomic mass for the isotopes below to 5 decimal places:
mass number
exact weight
percent abundance 12
98.90 13
1.10
amu

9. Average Atomic Mass
Calculate the average atomic mass for the isotope below and take it out 5 decimal place:
mass number
exact weight
percent abundance 14
99.63 15
0.37
amu

10. EMPIRICAL FORMULA
What is the empirical formula for a compound that is 26.56% Potassium, % Chromium, and 38.03% oxygen?
K2Cr2O7

11. EMPIRICAL FORMULA
What is the empirical formula for a compound that is 29.44% calcium, 23.55% sulfur, and 47.01% oxygen? This compound is an ingredient in plaster.
CaSO4

12. MOLECULAR FORMULA
A compound is 75.46% carbon, 4.43% hydrogen, and 20.10% oxygen by mass. It has a molecular weight of g/mol. What is the molecular formula for this compound?
C10H7O2 – empirical formula
C20H14O4 – molecular formula

13. MOLECULAR FORMULA
Ribose is a type of sugar consisting of 40% carbon, 6.7% hydrogen, and 53.3 % oxygen. A mass spectrometer was used to determine the molar mass of ribose to be 150 g/mol. What is the molecular formula for ribose ?
CH2O – empirical formula
C5H10O5 – molecular formula

14. % COMPOsition
Bicarbonate of soda (sodium hydrogen carbonate) is used in many commercial preparations. Its formula is NaHCO3. Find the mass percentages (mass %) of Na, H, C, and O in sodium hydrogen carbonate.
mass % Na = g / g x 100 = % mass % H = 1.01 g / g x 100 = 1.20 % mass % C = g / g x 100 = % mass % O = g / g x 100 = %

15. CONGRATULATIONS!!!!! STUDY! STUDY! STUDY! STUDY! Molar Mass Problems
Mole Conversions
Percent Composition
Average atomic mass
Molecular and Empirical formulas