CHEM 3: Polarity, VSEPR Theory and Gas Laws
1. Using the table of electronegativities provided below, rank these bonds from least polar to most
polar.
LEAST polar (most nonpolar) to
MOST polar
 C-F < P-Cl < S-Br < Br-Br < H-F
 S-Br < Br-Br < C-F < P-Cl < H-F
 S-Br < Br-Br < P-Cl < C-F < H-F
 Br-Br < S-Br < P-Cl < H-F < C-F
 Br-Br < S-Br < H-F < C-F < P-Cl
 S-Br < Br-Br < P-Cl < H-F < C-F
 Br-Br < C-F < P-Cl < S-Br < H-F
 Br-Br < S-Br < C-F < P-Cl < H-F
 Br-Br < S-Br < P-Cl < C-F < H-F
2. What is the molecular geometry of the central carbon in Cl2CO?
3. What is the molecular geometry of the central phosphorus in phosphite (PO33-)?
4. MARK ALL THAT APPLY: Which molecules below are POLAR?
HINT: Be sure to consider the three-dimensional shape and symmetry (or asymmetry) of the
molecule overall. As inherently limiting two-dimensional drawings, the Lewis dot structures do
NOT necessarily reflect the spatial arrangements of the atoms in the larger molecule.
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Sulfur dioxide
Sulfur trioxide
Carbon disulfide
Nitrogen trifluoride
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Useful conversions & constants that will be provided on an exam:
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R (the universal gas constant) = 0.082057 L·atm/K·mol = 62.363 L·mmHg·K-1mol-1
Kelvin = oC + 273.15
Standard Temperature & Pressure (STP) = 273.15 K & 1.000 bar of pressure = 0.00 oC & 0.987 atm
5. A cylinder with a moveable piston contains 218 mL of nitrogen gas (N2) at a pressure of 1.32 atm
& a temperature of 25 oC. What must the final volume be (in mL) for the pressure of the gas to
rise to 1.55 atm at a temperature of 335 K?
6. Assuming all gases are at STP, how many milliliters of oxygen gas would be needed for a
complete combustion of 550. mL of propane gas (C3H8)?
7. What is the density of butane gas (CH3CH2CH2CH3) in g/L at standard temperature and pressure
(STP)? Report the final answer to THREE SIGNIFICANT FIGURES.
8. What is the density of butane gas (CH3CH2CH2CH3) in g/L at 22.5 oC & a pressure of 765 mmHg?
9. Consider the combustion of 12 gallons of liquid octane (C8H18).
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What volume of oxygen gas is needed (in Liters) for this combustion of octane assuming the
temperature is 25 oC and the pressure is 0.98 atm?
o HINT: the density of liquid octane is 0.703 g/mL & 1 gallon = 3.78541 L
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Assuming the gases produced are at the same temperature and pressure, what volume of carbon
dioxide gas (in L) would be generated?