Unit 6 Test--Impure Thoughts: Solutions, Solubility, and Ions

Multiple Choice (Choose the best answer.)

  1. A glass of iced tea containing excess sugar at the bottom is said to be:

    saturated

    unsaturated

    heterogeneous

    both a) and c)

    both b) and c)

  2. A concentrated solution is one in which there is a:

    small amount of solvent

    small amount of solute

    large amount of solute in a small amount of solvent

    large amount of solute in a large amount of solvent

    none of the above

  3. Which of the following is a FALSE statement about electric charge?

    There are only two kinds of electric charge.

    Unlike charges attract.

    Like charges repel.

    Ions are created by the addition or subtraction of an electron to a neutral element.

    Why two positive charges repel each other is well explained by modern theory.

  4. Which of the following would likely conduct electricity?

    I. CO2 (aq)

    II. C12H22O11 (aq)

    III. KI (s)

    IV. KI (aq)

    IV only

    I, II, & IV only

    III & IV only

    I & II only

    none are correct

    Questions 5 - 7 are about solutions of CdCl2. The molar mass of cadmium chloride is 183 g.
  5. If 300 mL of a solution contains 18.3 g CdCl2, the molarity of the solution is:

    0.2 M

    0.040 M

    0.10 M

    0.033 M

    none of these values

  6. The solubility is sufficient so that a 9 M solution of CdCl2 can be made. What mass of CdCl2 would be present in 10.0 mL of 9 M solution?

    0.90 g

    3.47 g

    16.5 g

    21.3 g

    1.65 g

  7. Consider these statements about boiling a CdCl2 solution. Select the FALSE statement.

    The freezing temperature of the solution is higher than the freezing temperature of pure water.

    The boiling temperature of the solution will be higher than that of pure water (at the same pressure).

    The boiling temperature of the solution will rise as the solvent boils away.

    As boiling continues, the concentration of CdCl2 in solution will increase.

    The solution boils when its vapor pressure is equal to the atmospheric pressure.

  8. Which of the following statements is FALSE concerning a cadmium ion, Cd2+?

    It contains two more protons than electrons.

    It is formed by removing electrons from a neutral atom.

    It would be attracted to an NO3- ion.

    It is formed by adding two protons to a neutral atom.

    If it gained two electrons, it would be electrically neutral.

  9. The most concentrated solution from among those listed is:

    100 mL 0.25 M KCl

    150 mL 0.18 M NaOH

    75 mL 0.27 M KNO3

    200 mL 0.25 M NaNO3

    It is impossible to tell.

  10. Which of the following represents the formation of a chloride ion from a chlorine atom?

    Cl + e- Cl-

    Cl Cl + e-

    Cl Cl- + p+

    Cl- Cl- + e-

    Cl2 2 Cl- + 2e-

Problem-Solving (Show all work and units. Pay attention to significant figures.)

1. An aqueous solution of sodium sulfate was mixed with an aqueous solution of barium nitrate.

a) Write the ionic reaction. (If no reaction occurs, write the dissolution reactions for sodium sulfate and barium nitrate.)

 


b) If a reaction occurs, write the net ionic reaction.

 

2. What mass of KNO3, potassium nitrate, is needed to make 3.00 x 102 mL of a 2.00 M solution? Describe how to make the solution.

 

 

3. Which of the following ionic compounds will dissolve in water? For soluble compounds, write dissolution (dissolving) reactions.

a) (NH4)2SO4
b) Pb(NO3)2
c) BaS
d) Al(OH)3


4. In Experiment 16A, 40.0 mL of 0.50 M HCl (aq) reacted with an excess of CaCO3 (s) to form CO2 (g), H2O (l) and CaCl2 (aq). How many grams of CaCO3 (At. Wt. = 100 g/mol) reacted? Don't forget to write a balanced reaction.

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