Chemistry 12 Test 2001

1. Consider the following experiment:

1.0 mL 0.20 M Ag+      +          an unknown solution             precipitate

1.0 mL 020 M Sr2+      +          an unknown solution             no precipitate

The unknown solution could contain

A         0.20 M OH-    low with Ag+ and high with Sr2+

B          0.20 M NO3-

C         0.20 M PO43-

D         0.20 M SO42-

2. A compound has a solubility of 7.1  x  10-5 M at 25 oC. The compound is

A         CuS

B          AgBr

C         CaCO3            square the solubility

D         CaSO4

3. A saturated solution of NaCl contains 36.5 g of solute in 0.100 L of solution. The solubility of the compound is

A         0.062 M

B          1.60 M

C         3.65 M

D         6.24 M

4. Calculate the [Li+] in 200.0 mL of 1.5 M Li2SO4.

A         0.30 M

B          0.60 M

C         1.5 M

D         3.0 M  Do not divide by L

5. The Ksp expression for a saturated solution of Mg(OH)2 is

A         Ksp  =  [Mg2+][OH-]2

[Mg(OH)2]

B         Ksp  =  [Mg2+][OH-]2

C         Ksp  =  [Mg2+][OH-]

D         Ksp  =  [Mg2+][2OH-]2

6. Consider the following saturated solution solutions

CuSO4             BaSO4             CaSO4

The order of cation concentration, from highest to lowest, is

A         [Ba2+]               >          [Ca2+]              >          [Cu2+]

B          [Ca2+]              >          [Cu2+]              >          [Ba2+]

C         [Cu2+]              >          [Ca2+]              >          [Ba2+]  largest to smallest Ksp

D         [Cu2+]              >          [Ba2+]               >          [Ca2+]

7. When 1.0  x  10-3 moles of CuCl2(s) are added to 1.0 L of 1.0  x  10-3 M IO3-, the

A         Trial Ksp > Ksp and a precipitate forms

B          Trial Ksp < Ksp and a precipitate forms

C         Trial Ksp > Ksp and no precipitate forms

D         Trial Ksp < Ksp and no precipitate forms

8. The solubility of CdS = 2.8 x 10-14 M. The value of the Ksp is

A         7.8  x  10-28      Square the solubility

B          2.8  x  10-14

C         5.6  x  10-14

D         1.7  x  10-7

9. The ion concentrations in 0.25 M Al2(SO4)3 are

[Al3+]               [SO42-]

A         0.25 M             0.25 M

B         0.50 M                        0.75 M

C         0.75 M             0.50 M

D         0.10 M             0.15 M

10. Which of the following will not produce a precipitate when equal volumes of 0.20 M solutions are combined?

A         KOH and CaCl2

B          Zn(NO3)2 and K3PO4

C         Sr(OH)2 and (NH4)2S Both have high solubility

D         Na2SO4 and Pb(NO3)2

11. Consider the following equilibrium: Mg(OH)2(s)    Mg2+(aq)  +  2OH-(aq)

A compound that can be added to cause a shift to the right is

A         NaOH

B         HCl     Acids react with OH-

C         Sr(OH)2

D         Mg(OH)2

12. If the trial ion product for AgBrO3 is calculated to be 1.0  x  10-7, then

A         a precipitate forms because the trial ion product > Ksp

B          a precipitate forms because the trial ion product < Ksp

C         no a precipitate forms because the trial ion product > Ksp

D         no a precipitate forms because the trial ion product < Ksp

13.Which of the following will dissolve in water to produce a molecular solution?

A         CaCl2

B          NaOH

C         CH3OH           One of these things is not kike the other

D         Sr(OH)2

14. In a solubility equilibrium, the

A         rate of dissolving equals the rate of crystallization

B          neither dissolving or crystallization occurs

C         concentration of solute and solvent are equal

D         mass of dissolved solute is greater than the mass of the solution

15. The maximum [SO42-] that can exist in 1.0  x  10-3 M Ca(NO3)2 without a precipitate forming is

A         7.1  x 10-5 M

B          1.0  x 10-3 M

C         8.4  x 10-3 M

D         7.1  x 10-2 M

16. When equal volumes of 0.20 M CuSO4(aq) and 020 M Li2S(aq)  are combined, the complete ionic equation is

A         Cu2+(aq) +          S2-(aq)                         CuS(s)

B          CuSO4(aq)         +          Li2S(aq)          CuS(s)               +          Li2SO4(s)

C         Cu2+(aq)  +  SO42-(aq)  +  2Li+(aq)   + S2-(aq)                    Li2SO4(aq)               +          CuS(s)

D         Cu2+(aq)              +  SO42-(aq)  +  2Li(aq)  +  S2-(aq)     CuS(s)     +     2Li+(aq)      + SO42-(aq)

17. Consider the solubility equilibrium:   CaCO3(aq)    Ca2+(aq)  +  CO32-(aq)

An additional piece of solid CaCO3 is added to the equilibrium above. The rate of dissolving and the rate of crystallization have

Rate of Dissolving                     Rate of crystallization

A                     increases                                increases

B                      increases                                  not changed

C                     not changed                              increased

D                     not changed                              not changed

18. At 25 oC, which of the following compounds would dissolve to form a saturated solution with the greatest [Pb2+]?

A         PbI2

B         PbCl2               largest Ksp

C         PbBr2

D         Pb(IO3)2

19. Consider the following anions:

I           10.0 mL of 0.20 M Cl-

II          10.0 mL of 0.20 M OH-

III        10.0 mL of 0.20 M SO32-

When 10.0 mL of 0.20 M Pb(NO3)2 are added to each of the above, precipitates form in

A         I and II only

B          I and III only

C         II and III only

D         I, II, and III

20. Which of the following units could be used to describe solubility?

A         g/s

B         g/L

C         M/L

D         mol/s

21. The solubility of SnS is 3.2 x 10-3 M. The value of the Ksp is

A         1.0  x  10-5       square the solubility

B          3.2  x  10-3

C         6.4  x  10-3

D         5.7  x  10-2

22. Silver chloride, AgCl, would be least soluble in

A         1.0 M HCl

B          1.0 M NaNO3

C         1.0 M ZnCl2

D         1.0 M AgNO3

23. The solubility of SrF2 is

A         4.3  x  10-9

B          6.6  x  10-5

C         1.0  x  10-3       square-root the Ksp

D         1.6  x  10-3

24. The Ksp expression for a saturated solution of AgCO3 is

A         Ksp  =  [Ag2+][CO32-]

B         Ksp  =  [Ag+]2[CO32-]

C         Ksp  =  [2Ag+][CO32-]

D         Ksp  =  [2Ag+]2[CO32-]

25. How many moles of solute are dissolved in 200.0 mL of a saturated solution of FeS?

A         1.2  x  10-19

B          6.0  x  10-19

C         1.5  x  10-10

D         7.7  x  10-10

26. A solution contains both Ag+ and Mg2+ ions. During selective precipitation, these ions are removed one at a time by adding

A         I- followed by OH-

B          OH- followed by S2-

C         SO42- followed by Cl-

D         NO3- followed by PO43-

27. Which of the following does not define solubility?

A         the concentration of solute in a saturated solution

B         the moles of solute dissolved in a given amount of solution

C         the maximum mass of solute that can dissolve in a given amount of solution

D         the minimum amount of solute required to produce one litre of saturated solution

28. The ion concentrations in 0.25 M Al2(SO4)3 are

[Al3+]               [SO42-]

A                     0.25 M             0.25 M

B                     0.50 M                        0.75 M

C                     0.75 M             0.50 M

D                     0.10 M             0.15 M

29. Which of the following will not produce a precipitate when equal volumes of 0.20 M solutions are combined?

A         KOH and SrCl2

B          Zn(OH)2 and K3PO4

C         Zn(OH)2 and (NH4)2S

D         Na2SO4 and Pb(NO3)2

30. What is observed when H2SO4 is added to a saturated solution of CaSO4?

A         CaSO4(s) dissolves

B          the [Ca2+] increases

C         bubbles of H2 are given off

31. The solubility of CdS is 2.8  x  10-14 M. The value of the Ksp is

A         7.8  x  10-28

B          2.8  x  10-14

C         5.6  x  10-14

D         1.7  x  10-7

32. Consider the following solutions: 0.10 M Cl-            0.10 M Br-       0.10 M IO3-     0.10 M BrO3-

Equal moles of AgNO3 are added to each solution. It is observed that a precipitate forms in all but one solution. Which solution does not form a precipitate?

A         Cl-

B          Br-

C         IO3-

D         BrO3-    highest Ksp

33. Consider the following equilibrium: 2O3(g)        3O2(g)    Keq  =  65

Initially, 0.10 mole O3 and 0.10 mole of O2 are placed in a 1.0 L container. Which of the following describes the changes in concentrations as the reaction proceeds to equilibrium?

[O3]                             [O2]

A         decreases                     decreases

B         decreases                   increases

C         increases                      decreases

D         increases                      increases

34.Consider the following potential energy diagram for the reversible reaction. Activation Energy (kJ)              ΔH (kJ)

A                     10                                                        -20

B                      10                                                        -30

C                     30                                                        +10

D                     20                                                        +30

35. Increasing the temperature of a reaction increases the rate by

I           increasing frequency of collision

II          increasing the kinetic energy of collision

III        decreasing the potential energy of collision

A         I only

B         I and II only

C         II and III only

D         I, II, and III

36. What is the Keq expression for the following equilibrium?

Fe (s)   +  4H2O(g)    Fe3O4(s)  +  4H2(g)

A         Keq  =  [H2]4

B          Keq  =  [H2]

[H2O]

C         Keq  =  [H2]4

[H2O]4

D         Keq  =   [Fe3O4][H2]4

[Fe]3[H2O]4

Subjective

1. Write the net ionic equation representing the reaction that occurs when 50.0 mL of 0.20 M ZnSO4 and 50.0 mL 0.20 M BaS are combined.

ZnSO4(aq)   +   BaS(aq)     BaSO4(s)   +  ZnS(s)

Zn2+   +   SO42-    +   Ba2+   +   S2-       BaSO4(s)     +      ZnS(s)

Zn2+   +   SO42-    +   Ba2+   +   S2-       BaSO4(s)     +      ZnS(s)

2. A 100.0 mL sample of 0.600M Ca(NO3)2 is diluted by adding 400.0 mL of water. Calculate the concentrations of all of the ions.

Ca(NO3)2                Ca2+     +          2NO3-

(100)    0.600 M                      0.120 M          0.240 M

(500)

3. When 1.00 L of CaF2 was evaporated to dryness, 2.66  x  10-2 g of residue was formed. Calculate the Ksp.

Molarity  =     2.66  x  10-2 g  x  1 mole

78.1 g          =   3.406  x  10-4 M

1.00 L

CaF2                                                Ca2+                 +                      2F-

3.406  x  10-4 M                                  3.406  x  10-4 M                      6.812  x  10-4 M

Ksp     =  (3.406  x  10-4 )(6.812  x  10-4) 2

=   1.58  x  10-10

4. A maximum of 0.60 g Pb(NO3)2 can be added to 1.5 L of 0.100 M NaBr(aq) without forming a precipitate. Calculate the [NaBr].

Molarity  =     0.60 g  x  1 mole

331.2 g        =   0.001208 M

1.5 L

PbBr2                                              Pb2+                 +                      2Br-

0.001208 M                            0.100 M

Ksp  =  [Pb2+][Br-]2

Ksp  =  [0.001208][0.100]2

Ksp  =  1.21  x  10 -5

5. Consider the following solutions at 25 oC saturated AgCl(aq)                                                          saturated Ag2CO3(aq)

Using calculations, identify the solution with the greater [Ag+].

AgCl(s)        Ag+   +              Cl-                                Ag2CO3(s)                 2Ag+    +          CO32-

x                      x                      x                                  x                                  2x                    x

Ksp     =          x2                                                                     Ksp  =  4x3

1.8  x  10-10  =  x2                                                                    8.5  x  10-12  =  4x3

x          =          1.3  x  10-5 M                                                  x          =          1.286  x  10-4 M

[Ag+]  =  1.3  x  10-5 M                                                           [Ag+]  =  2x   =   2.6  x  10-4 M

Greater