MW
TTh
MW
Student Name _______________________________ _______________
am mid pm
Post-Lab Questions:
Lab Section (circle one)
1. Based on the masses of the substances below, fill in the table by calculating molar masses, mole
quantities, & number of particles (atoms & molecules, where applicable).
Show your work for the last compound, carbon tetrachloride.
Substance
He
H2
O2
CCl4
Molar
Mass
(g/mol)
Mass (g)
Number of
moles
Number of
Molecules
Number of Atoms
10.984
21.968
40.891
Total:
Total:
Carbon:
Carbon:
Chlorine:
Chlorine:
120.8389
2. Consider 5.443 g of the substance lead (II) nitrate.
a) How many moles of Pb(NO3)2 formula units are present in this mass? How many formula units
does this represent? 1 formula unit = 1 Pb(NO3)2
b) How many moles of Pb atoms are present in this mass? How many Pb atoms does this
represent?
c) How many moles of nitrate ions are present in this mass? How many nitrate ions does this
represent?
d) How many moles of oxygen atoms are present? How many O atoms does this represent?
3. A. The distance (based on a direct path) between San Francisco and Los Angeles is 558.68 km.
Calculate how many iodine atoms (diameter = 2.66 x 10-10 m) would be needed to stack end to end
to span this distance.
3. B. The density of solid iodine is 4.93 g/cm3. What volume of solid iodine would contain the same
number of iodine atoms as calculated Part A above?
4. Assume you won the lottery and were award one mole of US dollars. If you spent one billion dollars
per second, how many years would it take to run out of your lottery winnings?
5. The density of aluminum is 2.71 g/cm3. How many aluminum atoms are contained within 1.50 grams
of aluminum?
6. Using information from the previous problem calculate the volume occupied by a single aluminum
atom.
7. The average energy required to break a carbon-carbon single bond is 6.49 x 10-19 Joules. Calculate
the energy required to break 1.00 moles of carbon-carbon single bonds.
8. How many TOTAL atoms are contained within a sample of water with a volume of 14.78 mL (1
tablespoon)? Assume a density of 0.9982 g/mL. Compare this to the estimated number of stars in
our universe (approximately 10,000,000,000,000,000,000,000 stars)—which is larger?