Answers
to Self Test on Solutions
Short essay questions
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1.
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Explain why water is such a good solvent
for polar compounds and ionic compounds.
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Water is a good solvent
because it is polar. It is attracted to other polar
molecules, positive ions, and negative ions.
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2.
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What relationship is there between
Henry's law and the concentration of dissolved gases in the
blood? When the partial pressure of oxygen is 159 mm Hg the
concentration of dissolved oxygen in the blood can be 0.44
g/ 100 mL of blood. What will happen to the concentration of
dissolved oxygen if the oxygen pressure goes down to 56 mm
Hg? Why are people with breathing problems placed in an
oxygen rich atmosphere?
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The concentraion of
dissolved gases depends on the partial pressure of the
individual gas. The higher the partial pressure for the gas
the higher the concentration.
When the partial pressure
for oxygen, O2, falls from 159 mm Hg to 56 mm Hg
the concentration will decrease. The actual new
concentration will be
C = (C initial) x( 56 mm
Hg of O2 pressure /159 mm Hg of O2
pressure)
C = (0.44 g/ 100 mL) x(
56 mm Hg of O2 pressure /159 mm Hg of
O2 pressure)
C = (0.15 g/ 100
mL)
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3.
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A person's health is connected to the
electrolyte balance in their body. Which of the following
cations has the highest concentration in blood plasma?
Na+, Ca2+, K+,
Mg2+.
The inorganic anions Cl1-,
HCO3-, SO42-, and
HPO42- are also present in plasma. The
concentrations of these anions do not equal the
concentrations of the cations. How is the electrical balance
maintained if these ions do not cancel each
other?
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The organic anions in the
blood from protein anions and anions from organic acids make
up the rest of the required negative charge.
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1.
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A solution of electrolytes will conduct
electricity.
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a. true
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b. false
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2.
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Which of the following is the most
concentrated solution?
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a. a mixture of 4000 mL of water and 2
mols NaOH
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b. a mixture of 2000 mL of water and 2
mols of HCl
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c. a mixture that gives 2000 mL of
solution containing 4 mols of NH3
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d. a mixture that gives a
solution of 2000 mL containing 6 mols of
NH3
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3.
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Henry's law predicts which of the
following?
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a. the concentration of dissolved acid in
a solution
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b. the concentration of
dissolved gas in a solution
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c. the concentration of
dissolved base in a
solution
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d. the concentration of acid needed to
neutralize a base
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4.
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Water is the solute in which of the
following mixtures?
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a. 100 mL of water and 20 grams of
NaCl
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b. 100 mL of water and
200 mL of ethanol
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c. 1000
mL of water and 3 mols of NaOH
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d. 2 liters of aqueous solution
containing 40 grams of NaOH
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5.
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The amount of dissolved gas in a solution
will generally .......
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a. increase when the pressure of the gas
decreases
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b. decrease when the
pressure of the gas decreases
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c. decrease when the temperature of the
solution decreases
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d. not change with pressure
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6.
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Which of the following is a
nonelectrolyte?
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a. NaCl
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b. HCl
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c. NaHCO3
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d.
CH3OH
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7.
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How many mols of CaCl2 are
dissolved in 250 mL of a 0.30 M CaCl2
solution?
1 mol CaCl2 =
111
g CaCl2
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a.
(0.250)(0.30)
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b. (0.250) / (0.30)
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c. (0.30) x (250)
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d. (0.250)
x (111) / 0.30
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8.
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Which of the following statements is
not true?
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a. all solutions are
colorless
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b. suspensions are not
transparent
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c. all the particles in a solution are
atomic or molecular in size
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d. all solutions are
homogeneous
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9.
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How many mols of HCl are dissolved in
60.0 mL of a 0.200 M HCl solution?
1 mol HCl = 36.5 g HCl ; 1 liter = 1000
mL
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a. 60.0 x 0.200
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b. 0.060 x
0.200
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c. 60.0 / 0.200
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d. 36.5 x 0.060 x 0.200
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10.
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What is the molarity of a solution made
by dissolving 1.25 mol of HCl in enough water to make 625 mL
of solution?
1 mol HCl = 36.5 g HCl ; 1 liter = 1000
mL
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a. 1.25 x 0.625 x 36.5
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b. 1.25 x 36.5 / 625
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c. 625 /1.25
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d. 1.25 /
0.625
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11.
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A 50.0 mL sample of 12.0 M HCl is diluted
to 200 mL. What is true about the diluted
solution?
1 mol HCl = 36.5 g HCl ; 1 liter = 1000
mL
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a. the number of mols of solute stays the
same
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b. the concentration of the solution goes
down to less than 6.0 M
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c. the number of grams of dissolved
solute stays the same
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d. all of
these
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12.
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Which of the following is the most
concentrated solution?
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a. a mixture of 300 mL of water and 20
grams NaOH
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b. a mixture of 2000 mL of water and 2
mols of HCl
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c. a mixture that gives 2000 mL of
solution containing 4 mols of NH3
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d. a mixture that
gives a solution of 1000 mL containing 4 mols of
NH3
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13.
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Which of the following describes a strong
electrolyte?
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a. a substance like NaCl that does not
dissociate to give ions
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b. a substance like CH3CH2CH2CH2CH2CH3
that does not dissociate to give ions
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c. a substance like
NaCl that dissociates completely to give ions
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d. a substance that dissociates somewhat
to give some ions
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14.
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Which of the following molecules is the
most polar and most soluble in water?
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