Low Solubility Equilibrium


CHEMISTRY  TEST                                                 NAME: _____________________

LOW SOLUBILITY EQUILIBRIUM                     DATE:  _____________________
Directions: For each of the following questions, choose the number that best answers the question and place it on your answer sheet.
Directions: For each of the following questions, all major steps must be shown to receive
full credit.

Low Solubility Equilibrium
Level 1
Multiple Choice

1. A solution that is saturated but dilute is
    1) Pb(NO3)2;                 2) BaCrO4;                  3) NaC1O3;                 4) K2CO3.
ANS: 2

2. A substance whose saturated solution is dilute is
    1) Na2SO4;                  2) CaBr2;                 3) Mg(NO3)2;                 4) PbC12.
ANS: 4

3. A substance whose saturated solution is dilute is
    1) K3PO4;                 2) MgBr2;                 3) CaSO4;                 3) AgNO3.
ANS: 3

4. A solution of BaC12 would be expected to produce all of the results listed below except:
    1) The solution is a good conductor of electricity.
    2) The solution is electrically neutral.
    3) The temperature of solution remains constant as it boils in an open beaker.
    4) The solution has a higher boiling temperature than pure water, both at room pressure.
    5) When a few drops of 0.1 M AgNO3(aq) are added, a white precipitate forms.
ANS: 3

5. Which of the following positive ions forms a hydroxide that is very soluble in water?
    1) Ni+2                  2) A1+3                  3) Zn+2                  4) K+                  5) Mg+2
ANS: 4

6. Which of the following pair of ions would be expected to form a precipitate when dilute
    solutions are mixed?                                                                  
    1) Na+ and SO4-2                                              3) NH4+ and CO3-2
    2) Ba+2 and CO3-2                                            4) Na+ and S-2                                              5) Ba+2 and OH-
ANS: 2

7. Which ion would probably be used to precipitate Ra+2(aq)  from solution?
    1) C1-                 2) NO3-                  3) OH-                  4) S-2                   5) SO4-2
ANS: 5

8. Which of these positive ions forms a hydroxide that is very soluble in water?
    1) Ca+2                 2) A1+3               3) Rb+                 4) Mg+2                5) Zn+2
ANS: 3

9. A solution of a sodium salt that will not form a precipitate with 0.5 M Pb(NO3)2  is
    1) NaBr;            2) Na2SO4;           3) NaCH3COO;           4) Na3PO4;            5) Na2CO3.
ANS: 3

10. What is the formula of the precipitate that occurs in the following set of mixtures?




    1) DY                2) BY                3) AX                 4) CX                5) BX
ANS: 4


11. Equal volumes of several solutions at 0.10 molar concentration are mixed.
    The chart below indicates the interactions that took place between these solutions.
    What is the formula of the hypothetical compound that has low solubility?






    1) DY               2) BY                3) AX                 4) CX                 5) BX
ANS: 5


12. Note the chart of interactions of equal volumes of various 0.10 M aqueous solutions. 
    (Symbols of elements or ions have been replaced by capital letters, and soluble products
    are indicated by “S’.)   What is the formula of the precipitate?





  
 1) DY                 2)BY                  3) AX                  4) CX                5) BX
ANS: 3

13. In the reaction A+(aq)  +  B-(aq)  +  C+(aq)  +  D-(aq)  ⇄  CB(s)  +  A+(aq)  +  D-(aq)
    1) A+ and B- are the spectator ions.           
    2) Two new types of molecules form.         4) C+ and B- are the participating ions.
    3) No ions remain in solution.                     5) None of these satisfy the equation above.
ANS: 4

14. In the reaction between solutions of sodium chloride and silver nitrate    
    1) oxidation-reduction takes place;           2) the number of ions in the solution
    increases;           3) two ions react, and two ions are spectators;           4) two new
    molecules form;            5) none of these. 
ANS: 3

15. Complete the equation for the reaction between solutions of lead nitrate and
    ammonium sulfate:   Pb+2(aq)  +  2NO3-(aq)  +  2NH4+(aq)  +  S-2(aq)  ⇄
    1) 2NH4NO3(s)  +  Pb+2(aq)  +  S-2(aq).       3) (NH4)2S(s)  +  Pb+2(aq)  +  2NO3-(aq).         
    2) Pb(NO3)2(s)  +  2NH4+(aq)  +  S-2(aq).    4) PbS( s)  +  2NH4+(aq)  +  2NO3-(aq).
                                                                         5) None of these equations are correct.
ANS: 4

16. What is the net ionic equation for the reaction between potassium iodide solution
    and silver nitrate solution?
    1) K+(aq)  +  I-(aq)  à  KI(s)                      3) Ag+(aq)  +  NO3-(aq)  à  AgNO3(s)
    2) K+(aq)  +  NO3-(aq)  à  KNO3(s)           4) Ag+(aq)  +  I-(aq)  à  AgI(s)
                                                                        5) all of these equations
ANS: 4

17. When equal volumes of 0.1 M solutions of  FeCl3  and  NaOH  are mixed, a precipitate
    of Fe(OH)3  is produced.  Which of the following equations best represents the net ionic
    equation for the reaction?
    1) FeCl3(aq)  +  3 NaOH(aq)  à  Fe(OH)3(s)  +  3 NaCl(aq)
    2) Fe+3(aq)  +  3 C1-(aq)  +  Na+(aq)  +  OH-(aq)  à  Fe(OH)3(s)  +  3 NaCl(s)
    3) Fe+3(aq)  +  3 OH-(aq)  à  Fe(OH)3(s)
    4) Fe+3(aq)  +  3 Cl-(aq)  +  3 Na+(aq)  +  3 OH-(aq)  à  Fe(OH)3(s)  +  3 Na+(aq)  + 
        3 Cl-(aq)
    5) Fe+3(aq)  +  3 C1-(aq)  +  3 NaOH(aq)  à  Fe(OH)3(s)  +  3 Na+(aq)  +  3 Cl-(aq)
ANS: 3

18. What is the net ionic equation for the reaction between solutions of sodium chloride
    and silver nitrate?
    1) Na+(aq)  +  NO3~aq)  à  Na(s)  +  ½N2(g)  +  3/2 O2(g)
    2) Ag+(aq)  +  Cl-(aq)  à  Ag(s)  +  ½ C12(g)
    3) Ag+(aq)  +  Cl-(aq)  à   Ag+(aq)  +  Cl-aq)
    4) Ag+(aq)  +  Cl-(aq)  à  AgCl(s)
    5) none of these
ANS: 4

19. Which silver salt is most soluble in water?
    1) AgC1 - Ksp  =  1.1 x 10-10                          3) AgI - Ksp  =  1.5 x 10-16
    2) AgBr - Ksp  =  7.7 x 10-13                          4) Ag2S - Ksp  =  1.0 x 10-50
ANS: 1

20. Which sulfide compound forms the most concentrated saturated solution at 250C.?
    1) CdS – Ksp  =  3.6 x 10-29                        3) FeS – Ksp  =  1.3 x 10-17
    2) CoS – Ksp  =  3.0 x 10-26                      4) HgS – Ksp  =  9.9 x 10-53
ANS: 3

21. For a solid solute that has an endothermic heat of solution when dissolved in water,
      which of the following is true?
    1) Its lattice (crystal) energy is less than its energy of hydration.
    2) Its solubility will increase with an increase in temperature.
    3) Its solubility increases significantly with an increase in pressure.
    4) The value for ΔG for the solution process is positive.
    5) The entropy of the system decreases as the solute is dissolved.
ANS: 2

22. Which compound is least soluble?
    1) PtS  (Kps  =  8 x 10-23)                          3) FeS  (Ksp  =  4 x 10-19)  
    2) NiS  (Ksp  =  3 x 10-21)                         4) MnS (Ksp  =  1 x 10-16)
ANS: 1
23. Consider the system  AgCl(s)  ⇄  Ag+(aq)  +  C1-(aq)  at equilibrium. 
    As chloride ions are added to this system and the temperature is kept constant,
    the value of the equilibrium constant
    1) decreases;            2) increases;            3) remains the same;            4) none of these.
ANS: 3

24. The solubility product constant     1) is a relationship between solvent and solute;
    2) applies only to nonelectrolytes;           3) is a relationship between the ions in a
    saturated solution of a solid of limited solubility;          4) applies to solutions that
    are not in equilibrium;           5) increases when stirring is increased.
ANS: 3

25. What is the expression for the solubility product constant, Ksp, for this reaction?
    Al(OH)3(s)  ⇄  A1+3(aq)  +  3 OH-(aq)
    1) _[Al(OH)3] _              2) [Al+3][OH-]
         [Al+3][OH-]                     [Al(OH)3]              3) [Al+3][3OH-]             4) [Al+3][OH-]3
ANS: 4

26. What is the solubility product expression, Ksp, for this equation?
    CaF2(s)  ⇄  Ca+2(aq)  +   2 F-(aq)
    1) [CaF2]                2) [Ca+2]                 3) [Ca+2][2F-]                 4) [Ca+2][ F-]2
ANS: 4
27. Consider the equation:  BaCO3(s)  ⇄  Ba+2(aq)  +  CO3-2(aq).  Which is the expression
    for the solubility product constant, Ksp, of barium carbonate?
    1) _ [Ba+2] _                            3) _  [BaCO3] _
          [CO3-2]                                   [Ba+2][CO3-2]                     5) [BaCO3}[Ba+2][CO3-2]
    2) [Ba+2][CO3-2]                      4) [Ba+2][CO3-2]   
                                                            [BaCO3]
ANS: 2

28. Which equation has this expression for its equilibrium constant?   KE  =  [Ni+2(aq)] 
    1) Ni+2(aq)  +  Co+2(aq)  ⇄  NiCo+4(aq)                                                       [Co+2(aq)]
    2) Ni+2(aq)  +  Co+2(aq)  ⇄  NiCo+4(s)             4) Ni+2(aq)  +  Co(s)  ⇄  Nj(s)  +  Co+2(aq)
    3) Ni(s)  +  Co+2(aq)  ⇄  Ni+2(aq)  +  Co(s)     5) none of these equations
ANS: 3

29. What is the molar concentration of Ni+2(aq) in a saturated solution of NiS if     
    equilibrium constant is 1.4 x 10-24?
    1) 1.4 x 10-24 M                            3) 2.8 x 10-12 M
    2) 1.2 x 10-18 M                            4) 3.6 x 10-6 M                                         5) none of these
ANS: 5

30. A solution in equilibrium with a precipitate of Ag3PO4  was found, upon analysis,
    to con­tain 1.6 x l0-5 moles of PO4-3 per liter and 4.8 x 10-5 moles of Ag+ per liter.
    The solubility product constant for Ag3PO4 is
    1) 1.8 x 10-18;              2) 1.7 x 10-17;               3) 1.4 x 10-14;               4) 2.6 x 10-10.
ANS: 1

31. The solubility of strontium sulfate at room temperature is 8.0 x l0-4 moles per liter.
    The calculated equilibrium constant for this solute is:
    1) 6.4 x 10-9;           2) 1.6 x 10-7;            3) 6.4 x 10-7;           4) 8.0 x 10-4;           5) 4.0 x 10-4.
ANS: 3

32. A saturated solution of silver acetate, CH3COOAg, contains 2 x 10-3 mole of silver
    ions/liter of solution.  What is the solubility product constant for silver acetate?
    1) 4 x 10-3            2) 2 x 10-3            3) 2 x 10-5            4) 4 x 10-6            5) 2 x 10-6
ANS: 4




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