Extra Problems

1
Extra Problems
2

• Because of increasing evidence of damage to the
  ozone layer, chlorofluorocarbon (CFC) production
  was banned in 1996. However, there are about 100
  million auto air conditioners that stiss use
  CFC-12 (CF2Cl2). These air conditioners are
  recharged from stockpiled supplies of CFC-12.
• Continued

3

• If each of the 100 million automobiles contains
  1.1 kg of CFC-12 and leaks 25 of its CFC-12 into
  the atmosphere per year, how much Cl in kilograms
  is added to the atmosphere each year due to auto
  airconditioners? (Assume two significant figures
  for all calculations.)

4

• A pure copper cube has an edge length of 1.42 cm.
  How many copper atoms does it contain (volume of
  a cube (edge length)3, density of copper 8.96
  g/cm3.

5

• Fingernail-polish remover is primarily acetone
  (C3H6O). How many carbon atoms are in a bottle
  of acetone with a volume of 325 mL? (density of
  acetone 0.788 g/mL)

6

• Lakes that have been acidified by acid rain (HNO3
  and H2SO4) can be neutralized by a process called
  liming, in which limestone (CaCO3) is added to
  the acidified water. Write ionic and net ionic
  equations to show haw limestone reacts with
  nitric acid and sulfuric acid to neutralize them.
  How would you be able to tell if the
  neutralization process was working?

7
What solution can you add to each of the
following cation mixtures to precipitate one
cation while keeping the other ion in solution?

• Fe2 Pb2 ?
• K Ca2 ?
• Ag Ba2 ?
• Cu2 Hg22 ?
• Sr2 Hg22 ?
• NH4 Ca2 ?

8

• A solution contains one or more of the following
  ions Ag, Ca2, and Cu2. When sodium chloride
  is added to the solution, no precipitate occurs.
  When sodium sulfate is added to the solution, a
  white precipitate occurs. The precipitate is
  filtered off and sodium carbonate is added to the
  remaining solution, producing a precipitate.
  Which ions were present in the original solution?
  Write net ionic equations for the formation of
  each of the precipitates observed.

9

• A solution contains one or more of the following
  ions Hg22, Ba2, and Fe2. When potassium
  chloride is added to the solution, a precipitate
  forms. The precipitate is filtered off and sodium
  sulfate is added to the remaining solution,
  producing no precipitate. When potassium
  carbonate is added to the remaining solution, a
  precipitate occurs. Which ions were present in
  the original solution? Write net ionic equations
  for the formation of each of the precipitates
  observed.