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Chapter 13 exam

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
How many moles of ions are produced by the dissociation of 1 mol of MgCl2?
a.
0
c.
2 mol
b.
1 mol
d.
3 mol
 

 2. 
Which compound dissociates to produce the ions Ca2+(aq) and NO3–(aq)?
a.
CaNO3(s)
c.
Ca(NO3)2(s)
b.
Ca2NO3
d.
Ca2(NO3)3
 

 3. 
When solutions of two ionic compounds are combined and a solid forms, the process is called
a.
hydration.
c.
solvation.
b.
precipitation.
d.
dissociation.
 

 4. 
Precipitation is an example of what type of reaction?
a.
composition
c.
single-displacement
b.
decomposition
d.
double-displacement
 
 
Use the table below to answer the following questions.

General Solubility Guidelines
1. Most sodium, potassium, and ammonium compounds are soluble in water.
2. Most nitrates, acetates, and chlorates are soluble.
3. Most chlorides are soluble, except those of silver, mercury(I), and lead. Lead(II) chloride is soluble in hot water.
4. Most sulfates are soluble, except those of barium, strontium, and lead.
5. Most carbonates, phosphates, and silicates are insoluble, except those of sodium, potassium, and ammonium.
6. Most sulfides are insoluble, except those of calcium, strontium, sodium, potassium, and ammonium.
 

 5. 
Which of the following pairs of solutions produces a precipitate when combined?
a.
Cu(NO3)2 and NaCl
c.
Cu(NO3)2 and K2CO3
b.
Fe(NO3)3 and MgCl2
d.
CaCl2 and NaNO3
 

 6. 
What is the spectator ion in the equation Cu2+(aq) + Zn2+(aq) + 2S2–(aq) ® CuS(s) + ZnS(s)?
a.
Cu2+(aq)
c.
S2–(aq)
b.
Zn2+(aq)
d.
None of the above
 

 7. 
What is the net ionic equation for the precipitation reaction between silver nitrate solution and sodium sulfide solution?
a.
2Ag+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq) ® Ag2S(s) + 2Na+(aq) + 2NO3–(aq)
b.
2Ag+(aq) + S2–(aq) ® Ag2S(s)
c.
Na+(aq) + NO3–(aq) ® NaNO3(s)
d.
2Ag+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq) ® Ag2S(s) + 2NaNO3(s)
 

 8. 
The separation of ions that occurs when an ionic compound dissolves is called
a.
ionization.
c.
precipitation.
b.
dissociation.
d.
oxidation.
 

 9. 
Ions are formed from solute molecules by the action of the solvent in a process called
a.
ionization.
c.
precipitation.
b.
dissociation.
d.
oxidation.
 

 10. 
When a molecular substance ionizes in water,
a.
charged particles are formed, and the more electronegative atom becomes a negative ion.
b.
charged particles are formed, and the less electronegative atom becomes a negative ion.
c.
no charged particles are formed.
d.
ions that were already present are released.
 

 11. 
The formula for the hydronium ion is
a.
H+.
c.
H3O–.
b.
H2O+.
d.
H3O+.
 

 12. 
Dissolving HCl in water produces
a.
H3O+ and Cl–.
c.
H3OCl(aq).
b.
H+ and Cl–.
d.
H3O– and Cl+.
 

 13. 
Formation of a hydronium ion in HCl solution
a.
is favorable and does not release energy.
b.
is unfavorable and releases energy.
c.
is favorable and releases energy.
d.
is unfavorable and does not release energy.
 

 14. 
Which type of solute is present in aqueous solution predominantly as hydrated ions rather than as molecules?
a.
a weak electrolyte
c.
a nonelectrolyte
b.
a strong electrolyte
d.
a covalent electrolyte
 

 15. 
A compound of low solubility
a.
is always a strong electrolyte.
c.
may be a strong or a weak electrolyte.
b.
is always a weak electrolyte.
d.
is always a nonelectrolyte.
 

 16. 
Why is freezing-point depression a colligative property?
a.
It is inversely proportional to the molal concentration of a solution.
b.
It is directly proportional to the molal concentration of a solution.
c.
It does not depend on a molal freezing-point constant for each solvent.
d.
It depends on the properties of an electrolyte in a solvent.
 

 17. 
Why is boiling-point elevation a colligative property?
a.
It is inversely proportional to the molal concentration of a solution.
b.
It is directly proportional to the molal concentration of a solution.
c.
It does not depend on a molal boiling-point constant for each solvent.
d.
It is independent of changes in vapor pressure.
 

 18. 
Why is osmotic pressure a colligative property?
a.
It depends on the rate of osmosis.
b.
It depends on the type of solute particles in two solutions of unequal concentrations.
c.
It depends on the concentration of solute particles in a solution.
d.
It depends on the type of solute particles in a solution.
 

 19. 
A water solution containing an unknown quantity of a nonelectrolyte solute has a freezing point of –0.665°C. What is the molal concentration of the solution if Kf = –1.86°C/m?
a.
0.010 m
c.
0.358 m
b.
0.355 m
d.
2.66 m
 

 20. 
What is the freezing-point depression of an aqueous solution of an electrolyte that produces three ions for every formula unit that dissociates if the electrolyte's concentration is 1.25 m?
Kf  = –1.86°C/m.
a.
–1.25°C
c.
–5.58°C
b.
–1.86°C
d.
–6.98°C
 

 21. 
What is the approximate freezing-point depression of a 0.010 m aqueous CaCl2 solution?
Kf  = –1.86°C/m.
a.
–0.019°C
c.
–0.056°C
b.
–0.037°C
d.
–0.074°C
 

 22. 
What is the approximate freezing-point depression of a 0.050 m aqueous Na2SO4 solution?
Kf  = –1.86°C/m.
a.
–0.11°C
c.
–0.22°C
b.
–0.28°C
d.
–0.39°C
 

 23. 
The Debye-Hückel theory accounts for
a.
attraction between ions in solutions.
b.
repulsion between ions in solution.
c.
attraction between ions in crystals.
d.
the greater freezing-point depressions in electrolyte solutions than in nonelectrolyte solutions.
 

 24. 
Electrolytes affect colligative properties differently than do nonelectrolytes because electrolytes
a.
are volatile.
b.
have lower boiling points.
c.
produce fewer moles of solute particles per mole of solute.
d.
produce more moles of solute particles per mole of solute.
 

 25. 
As electrolyte concentration decreases, freezing-point depression
a.
approaches the value calculated by assuming complete ionization.
b.
gets farther from the value calculated by assuming complete ionization.
c.
remains exactly equal to the value calculated by assuming complete ionization.
d.
approaches 0°C.
 



 
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