Solubility                                Quiz #6                       Separating Ions      Answers

 

 

1.         During a lab on qualitative analysis, an unknown solution containing one cation was analyzed and the

            following data were collected:

 

0.2 M Anions Added to the Unknown Solution

Observation

S2-

no precipitate

SO42-

precipitate

OH-

precipitate

CO32-

precipitate

 

            Which one of the following cations is found in the unknown solution?

            A.        Mg2+

            B.        Be2+

            C.        Sr2+

            D.        Ba2+

 

2.         Which of the following could be used to precipitate both Mg2+ and Ca2+ from hard water?

            A.        Lithium sulphate

            B.        Sodium phosphate

            C.        Potassium sulphide

            D.        Ammonium chloride

 

3.         A reagent that may be used to separate Cl- from S2- by precipitation is

            A.        KNO3

            B.        AgNO3

            C.        Pb(NO3)2

            D.        Al(NO3)3

 

4.         The precipitate formed when equal volumes of 0.2 M Sr(OH)2 and 0.2 M MgS are mixed is

 

            A.        SrS

            B.        Mg(OH)2

            C.        a mixture of Mg(OH)3 and SrS

            D.        a mixture of Sr(OH)2 and MgS

 

5.         Which of the following ions could be used to separate Cl-(aq) from SO42-(aq) by precipitation?

 

            A.        Ag+

            B.        Ca2+

            C.        NH4+

            D.        Pb2+       

 

6.         Which of the following ions could be added to an aqueous mixture containing Pb2+ and Ba2+

            to separate the ions by precipitating one of them?

 

            A.        I-

            B.        NO3-

            C.        PO43-

            D.        SO42-        

 

7.         Which of the following would precipitate the Ca2+ and Mg2+ found in hard water?

 

            A.        S2-

            B.        PO43-

            C.        SO42-

            D.        CH3COO-

 

8.         A solution containing an unknown cation was added to three solutions and the following observations were recorded:

 

SOLUTION

OBSERVATION

NaI

no precipitate

Na2SO4

precipitate

NaOH

no precipitate

  

 

            The unknown cation is

 

            A.        Pb2+

            B.        Sr2+

            C.        Ca2+

            D.        Ag+       

 

9.         To remove Mg2+ from a solution by precipitation, a student should add

 

            A.        NaI

            B.        KOH

            C.        Li2SO4

            D.        (NH4)2S

 

10.       Which of the following could be used to separate Pb2+ from Ba2+ by precipitation?

 

            A.        Na2S   

            B.        NaOH

            C.        Na2CO3

            D.        Na3PO4

 

11.       A student wishes to identify an unknown cation in a solution. A precipitate does not form with the addition of  SO42-,

            but does form with the addition of S2-. Which of the following is the unknown cation?

 

            A.        Ag+

            B.        Mg2+

            C.        Ca2+

            D.        Cu2+ 

 

12.       A solution contains CO32- and OH- . Separation of these two anions by selective precipitation is accomplished 

            by first adding Sr(NO3)2 solution, then filtering and finally adding to the filtrate a solution of

 

            A.        HNO3

            B.        RbNO3

            C.        NH4NO3

            D.        Zn(NO3)2        

 

13.       A nitrate solution containing an unknown cation is added to each of the following three test tubes.

 

1.0 M NaOH
 

1.0 M Na2S
 

1.0 M Na2SO4
 
                                   

 

 

 

 

 

 

 

 

 

            A precipitate forms in one test tube only. The unknown cation is

 

            A. Ag+

            B. Ca2+

            C. Sr2+

            D. NH4+     

 

 

14.       A solution containing a single unknown cation is added to three test tubes. the following anions were added and observations were recorded.

 

           

TEST TUBE

ANION ADDED

OBSERVATION

1

SO42-

precipitate

2

S2-

precipitate

3

OH-

precipitate

 

 

            The solution contains

 

            A. Sr2+

            B. Ag+ or Pb2+

            C. Ca2+ or Ba2+

            D. K+, NH4+ or H+         

 

15.       Which of the following solutions could be used to separate the anions SO42- and CO32- from each other by precipitation?

            A.        NaNO3(aq)

            B.        AgNO3(aq)

            C.        Fe(NO3)3(aq)

            D.        Ba(NO3)2(aq)

 

16.       Which of the following solutions could be used to separate the anions PO43- and OH- from each other by precipitation?

            A.        NaNO3(aq)

            B.        AgNO3(aq)

            C.        Fe(NO3)3(aq)

            D.        Sr(NO3)2(aq)

 

17.       Which of the following solutions could be used to separate the anions S2- and OH- from each other by precipitation?

            A.        NaNO3(aq)

            B.        AgNO3(aq)

            C.        Fe(NO3)3(aq)

            D.        Ba(NO3)2(aq)

 

18.       Which of the following solutions could be used to separate the cations Ba2+ and Sr2+ from each other by precipitation?

            A.        NaNO3(aq)

            B.        Na2CO3(aq)

            C.        K2SO4(aq)

            D.        KOH(aq)

 

19.       Which of the following solutions could be used to separate the cations Ca2+ and Mg2+ from each other by  precipitation?

            A.        NaNO3(aq)

            B.        Na2CO3(aq)

            C.        K2SO4(aq)

            D.        KOH(aq)

20.       Which of the following solutions could be used to separate the cations Be2+ and Pb2+ from each other by precipitation?

            A.        NaCl(aq)

            B.        Na2CO3(aq)

            C.        KNO3(aq)

            D.        KOH(aq)

 

21.       Which sequence of chemicals, in the order listed, would successfully separate Sr2+, Ca2+, and Ag+?

           

            A.        NaCl(aq), Na2CO3(aq), and Na2SO4(aq)

            B.        NaCl(aq), Na2SO4(aq), and Na2CO3(aq)

            C.        Na2CO3(aq), NaCl(aq), and Na2SO4(aq)

            D.        NaCl(aq), NaOH(aq), and Na2CO3(aq)

 

22.       Which sequence of chemicals, in the order listed, would successfully separate Zn2+, Be2+, and Sr2+?

           

            A.        NaOH(aq), Na2CO3(aq), and Na2SO4(aq)

            B.        Na2S(aq), NaOH(aq), and Na2CO3(aq)

            C.        Na2CO3(aq), NaCl(aq), and Na2SO4(aq)

            D.        NaCl(aq), Na2SO4(aq), and Na2CO3(aq)

 

23.       Which sequence of chemicals, in the order listed, would successfully separate OH- , CO32-, and S2-?

            A.        NaNO3(aq) , Ba(NO3)2(aq), and Zn(NO3)2(aq)

            B.        AgNO3(aq), Ba(NO3)2(aq), and Zn(NO3)2(aq)

            C.        Fe(NO3)3(aq), Ba(NO3)2(aq), and Zn(NO3)2(aq)

            D.        Sr(NO3)2(aq), Ba(NO3)2(aq), and Zn(NO3)2(aq)

 

24.       Which sequence of chemicals, in the order listed, would successfully separate OH- , S2-, and SO42-?    

            A.        NaNO3(aq) , Zn(NO3)2(aq), and Ba(NO3)2(aq)

            B.        AgNO3(aq), Zn(NO3)2(aq), and Ba(NO3)2(aq)

            C.        Be(NO3)2(aq), Fe(NO3)3(aq), and Ba(NO3)2(aq)

            D.        Sr(NO3)2(aq), Zn(NO3)2(aq), and Pb(NO3)2(aq)

 

25.       Which sequence of chemicals, in the order listed, would successfully separate Cl-, CO32-, and S2-?

            A.        NaNO3(aq) , Zn(NO3)2(aq), and Ba(NO3)2(aq)

            B.        AgNO3(aq), Zn(NO3)2(aq), and Ba(NO3)2(aq)

            C.        Fe(NO3)3(aq), Zn(NO3)2(aq), and Ba(NO3)2(aq)

            D.        Sr(NO3)2(aq), Zn(NO3)2(aq), and AgNO3(aq)