Acids Unit Midterm Practice Test

 

1.         Consider the following:

 

I           H2CO3  +  F-  D  HCO3-  +  HF

II          HCO3-  +  HC2O4-  D  H2CO3  +  C2O42-

III        HCO3-  +  H2C6H6O7-  D  H2CO3  +  HC6H5O72-

 

The HCO3- is a base in

 

A.              I only

B.              I and II only

C.              II and III only

D.              I, II, and III

 

2.         Consider the following equilibrium for an indicator:

 

            HInd  +  H2O  D  Ind-  +  H3O+

 

When a few drops of indicator methyl red are added to 1.0 M HCl, the colour of the resulting solution is

 

A.        red and the products are favoured

B.        red and the reactants are favoured

C.        yellow and the products are favoured

D.        yellow and the reactants are favoured

 

3.         The volume of 0.200 M Sr(OH)2 needed to neutralize 50.0 mL of 0.200 M HI is

 

            A.        10.0 mL

            B.        25.0 mL

            C.        50.0 mL

            D.        100.0 mL

 

4.         The pOH of 0.050 M HCl is

 

            A.        0.050

            B.        1.30

            C.        12.70

            D.        13.70

 

5.         The volume of 0.450 M HCl needed to neutralize 40.0 mL of Sr(OH)2 is

 

            A.        18.0 mL

            B.        20.0 mL

            C.        40.0 mL

            D.        80.0 mL

 

6.         Consider the following

 

            I           H3PO4              II          H2PO4-             III        HPO42-             IV        PO43-

 

            Which of the following solutions will have the largest [H30+]?

 

            A.        I and II only

            B.        II and III only

            C.        I, II, and III only

            D.        II, III, and IV only

 

7.         Which of the following solutions will have the largest [H3O+]?

 

            A.        1.0 M HNO2

            B.        1.0 M H3BO3

                    C.        1.0 M H2C2O4

                    D.        1.0 M HCOOH

 

8.         Consider the following:          H2O  +  57 kJ  D  H3O+  +  OH-

 

            When the temperature of the system is increased, the equilibrium shifts

 

            A.        left and the Kw increases

            B.        left and the Kw decreases

            C.        right and the Kw increases

            D.        right and the Kw decreases

 

9.         Normal rainwater has a pH of approximately 6 as a result of dissolved

 

            A.        oxygen

            B.        carbon dioxide

            C.        sulphur dioxide

            D.        nitrogen dioxide

 

10.       A 1.0 M solution of sodium dihydrogen phosphate is

 

            A.        acidic and the pH < 7.00

            B.        acidic and the pH > 7.00

            C.        basic and the pH < 7.00

            D.        basic and the pH > 7.00

 

 

11.       Consider the following equilibrium for an indicator:

 

            HInd  +  H2O  D  Ind-  +  H3O+

 

When a few drops of indicator chlorophenol red are added to a colourless solution of pH 4.0, the resulting solution is

 

A.        red as [HInd] < [Ind-]

B.        red as [HInd] > [Ind-]

C.        yellow as [HInd] < [Ind-]

D.        yellow as [HInd] > [Ind-]

 

12.       A Bronsted-Lowry base is defined as a chemical species that

 

            A.        accepts protons

            B.        neutralizes acids

            C.        donated electrons

            D.        produces hydroxides ions in solution

 

13.       Which of the following solutions will have the greatest electrical conductivity?

 

            A.        1.0 M HCN

            B.        1.0 M H2SO4

            C.        1.0 M H3PO4

            D.        1.0 M CH3COOH

 

14.       Consider the following equilibrium:  HC6H5O72-  +  HIO3  D  H2C6H5O7-  +  IO3-

 

            The order of Bronsted-Lowry acids and bases is

 

            A.        acid, base, acid, base

            B.        acid, base, base, acid

            C.        base, acid, acid, base

            D.        base, acid, base acid

 

15.       Consider the following: H2O(l)  D  H+  +  OH-

 

When a small amount of 1.0 M KOH is added to the above system, the equilibrium

 

A.        shifts left and [H+] decreases

B.        shifts left and [H+] increases

C.        shifts right and [H+] decreases

D.        shifts right and [H+] increases

 

 

16.       Which of the following has the highest pH?

 

            A.        1.0 M NaIO3

            B.        1.0 M Na2CO3

                    C.        1.0 M Na3PO4

                    D.        1.0 M Na2SO4

 

17.       In a 100.0 mL sample of 0.0800 M NaOH the [H3O+] is

 

            A.        1.25  x  10-13 M

            B.        1.25  x  10-12 M

            C.        8.00  x  10-3 M

            D.        8.00  x  10-2 M

 

18.       Consider the following:

 

I           ammonium nitrate        II          calcium nitrate             III        iron III nitrate

 

When dissolved in water, which of these salts would form a neutral solution?

 

A.        II only

B.        III only

C.        I and III only

D.        I, II, and III

 

19.       Consider the following:  SO42-  +  HNO2  D  HSO4-  +  NO2-

 

            Equilibrium would favour the

 

            A.        the products since HSO4- is a weaker acid than HNO2

            B.        the reactants since HSO4- is a weaker acid than HNO2

                    C.        the products since HSO4- is a stronger acid than HNO2

            D.        the reactants since HSO4- is a stronger acid than HNO2

 

20.       The net ionic equation for the hydrolysis of Na2CO3 is

 

            A.        H2O  +  Na+  D  NaOH  + H+

            B.        H2O  +  2Na+  D  Na2O  + 2H+

            C.        H2O  +  CO32-  D  H2CO3  +  O2-

            D.        H2O  +  CO32-  D  HCO3-  +  OH-

 

21.       Consider the following equilibrium: 2H2O(l)  D  H3O+  +  OH-

 

            A few drops of 1.0 M HCl are added to the above system. When equilibrium is

re-established, the

 

A.        [H3O+] has increased and the [OH-] has decreased

B.        [H3O+] has increased and the [OH-] has increased

C.        [H3O+] has decreased and the [OH-] has increased

D.        [H3O+] has decreased and the [OH-] has decreased

 

22.       A basic solution

 

            A.        tastes sour

            B.        feels slippery

            C.        does not conduct electricity

            D.        reacts with metals to release oxygen gas

 

23.       The balanced formula equation for the neutralization of H2SO4 by KOH is

 

            A.        H2SO4  +  KOH    KSO4  +  H2O

            B.        H2SO4  +  KOH    K2SO4  +  H2O

            C.        H2SO4  +  2KOH    K2SO4  +  H2O

            D.        H2SO4  +  2KOH    K2SO4  +  2H2O

 

24.       An Arrhenius base is defined as a substance which

 

            A.        donates protons

            B.        donates electrons

            C.        produces H+ in solution

            D.        produces OH- in solution

 

25.       Consider the following equilibrium:  HS-  +  H3PO4  D  H2S  +  H2PO4-

            The order of Bronsted-Lowry acids and bases is

 

            A.        acid, base, acid, base.

            B.        acid, base, base, acid

            C.        base, acid, acid, base

            D.        base, acid, base, acid

 

26.       The equation representing the reaction of ethanoic acid with water is

 

            A.        CH3COO-  +  H2O  D  CH3COOH  +  OH-

            B.        CH3COO-  +  H2O  D  CH3COO2-  +  H3O+

            C.        CH3COOH  +  H2O  D  CH3COO-  +  H3O+

            D.        CH3COOH  +  H2O  D  CH3COOH2+  +  OH-

 

27.       Consider the following equilibrium:  2H2O  +  57kJ  D  H3O+  +  OH-

 

            When the temperature is decreased, the water

 

            A.        stays neutral and the [H3O+] increases

            B.        stays neutral and the [H3O+] decreases

            C.        becomes basic and [H3O+] decreases

            D.        becomes acidic and [H3O+] increases

 

28.       The equation for the reaction of Cl2O with water is

 

            A.        Cl2O  +  H2O  D  2HClO

            B.        Cl2O  +  H2O  D  2ClO  +  H2

            C.        Cl2O  +  H2O  D  Cl2  +  H2O2

            D.        Cl2O  +  H2O  D  Cl2  +  O2  +  H2

 

29.       The conjugate acid of C6H50- is

 

            A.        C6H4O-

            B.        C6H5OH

            C.        C6H4O2-

            D.        C6H5OH+

 

30.       Which of the following solutions will have the greatest electrical conductivity?

 

            A.        1.0 M HCl

            B.        1.0 M HNO2

C.        1.0 M H3BO3

D.        1.0 M HCOOH

 

31.       A solution of 1.0 M HF has

 

            A.        a lower pH than a solution of 1.0 M HCl

            B.        a higher pOH than a solution of 1.0 M HCl

            C.        a higher [OH-] than a solution of 1.0 M HCl

            D.        a higher [H3O+] than a solution of 1.0 M HCl

 

32.       Which of the following is the weakest acid

 

            A.        HIO3

            B.        HCN

            C.        HNO3

            D.        C6H5COOH

 

 

 

33.       Considering the following data

 

            H3AsO4            Ka  =  5.0  x  10-5

            H2AsO4-           Ka  =  8.0  x  10-8

            HAsO42-           Ka  =  6.0  x  10-10

 

            The Kb value for H2AsO4- is

 

            A.        2.0  x  10-10

            B.        8.0  x  10-8

            C.        1.2  x  10-7

D.        1.7  x  10-5

 

34.       In a solution at 25oC, the [H3O+] is 3.5  x  10-6 M. The [OH-] is

 

A.        3.5  x  10-20 M 

            B.        2.9  x  10-9 M

                    C.        1.0  x  10-7 M

            D.        3.5  x  10-6 M

 

35.       In a solution with a pOH of 4.22, the [OH-] is

 

A.        1.7  x  10-10 M 

            B.        6.0  x  10-5 M

                    C.        6.3  x  10-1 M

            D.        1.7  x  104 M

 

36.       An aqueous solution of NH4CN is

 

            A.        basic because Ka  <  Kb

            B.        basic because Ka  >  Kb

            C.        acidic because Ka  <  Kb

            D.        acidic because Ka  >  Kb

 

37.       The net ionic equation for the predominant hydrolysis reaction of KHSO4 is

 

            A.        HSO4-  +  H2O  D  SO42-  +  H3O+

            B.        HSO4-  +  H2O  D  H2SO4  +  OH-

            C.        KHSO4  +  H2O  D  K+  +  SO42-  +  H3O+

            D.        KHSO4  +  H2O  D  K+  +  H2SO4  +  OH-

 

38.       The [OH-] in an aqueous solution always equals

 

            A.        Kw  x  [H3O+]

            B.        Kw  -  [H3O+]

            C.        Kw/[H3O+]

            D.        [H3O+]/Kw

 

39.       The [H3O+] in a solution with pH of 0.253 is

 

A.        5.58  x  10-15 M           

            B.        1.79  x  10-14 M

                    C.        5.58  x  10-1 M

            D.        5.97  x  10-1 M

 

40.       The equilibrium expression for the hydrolysis reaction of 1.0 M K2HPO4 is

 

            A.        [H2PO4-][OH-]                       B.        [H3PO4][OH-] 

                            [HPO4-]                                  [H2PO4-]

           

C.        [K+] [KHPO4-]             D.        [K+]2 [HPO42-]

                            [K2HPO4]                                [K2HPO4]

 

41.       The solution with the highest pH is

 

            A.        1.0 M NaCl

            B.        1.0 M NaCN

            C.        1.0 M NaIO3

            D.        1.0 M Na2SO4

 

42.       The pH of 100.0 mL of 0.0050 M NaOH is

 

            A.        2.30

            B.        3.30

            C.        10.70

            D.        11.70

 

43.       Consider the following equilibrium for an indicator: HInd + H2O D Ind- + H3O+

 

            At the transition point,

 

            A.        [HInd]  >  [Ind-]

            B.        [HInd]  =  [Ind-]

            C.        [HInd]  <  [Ind-]

            D.        [HInd]  =  [H3O+]

 

 

Acids Unit Midterm Practice Test               Subjective

 

1.         a)         Write the net ionic equation for the reaction between NaHSO3 and NaHC2O4.

                       

                        HSO3-  +  HC2O4-  D  H2SO3  +  C2O42-

                       

            b)         Explain why the reactants are favoured in the above reaction.

 

                        H2SO3 is a stronger acid than HC2O4- 

 

 

2.         What is the [H3O+] in a solution formed by adding 60.0 mL of water to 40.0 mL of 0.400 mL of KOH?

 

                        KOH                                   K+        +          OH-

 

                        40      x  0.40 M                      0.16 M            0.16 M

                        100     

 

                        [H+][OH-]  =  1.00  x  10-14                [H+]  =  6.25  x  10-14 M

 

 

 

 

 

3.         A solution of 0.100 M HOCN has a pH of 2.24. Calculate the Ka value for the acid.

 

                       

                        Ka       =          10-2.24              =          0.005754 M

 

 

                        HOCN                        D                    H+                    +          OCN-

 

                        I           0.100 M                                  0                                  0

                        C         0.005754 M                            0.005754 M                0.005754 M

                        E         0.094245 M                            0.005754 M                0.005754 M

 

 

                       

                        Ka       =          (0.005754 )2    =          3.5  x  10-4

                                                  0.094245

 

 

 

4.         Calculate the pH in 100.0 mL M H3BO3.

 

 

                        H3B03                          D                    H+                    +          H2BO3-

 

                        I           0.400 M                                  0                                  0

                        C         x                                              x                                  x

                        E         0.400  -  x                                x                                  x

           

           

                                                               0       small Ka approximation

 

                        (x)2                  =                      7.3  x  10-10

                        0.400

 

 

                        x          =          1.709  x  10-5 M

 

                        pH       =          4.77

 

 

 

 

5.         Calculate the pH of the solution formed by mixing 20.0 mL of 0.500 M HCl with 30.0 mL of 0.300 M NaOH.

 

 

                                    HCl                                         +                      NaOH                                     NaCl               +                      H2O

 

0.0200 L  x  0.500 mole            =   0.01000 mole HCl          0.0300 L  x  0.500 mole            =   0.01000 mole NaOH

                              L                                                                                 L

 


I                                   0.00100   mole                                                0.000900 mole

 

C                                 0.000900  mole                                               0.000900 mole

 

E                                 0.00010    mole                                               0

 

 

 


                                                              Note the loss of significant figures!            Total new volume = 20.0 mL + 30.0 mL =  50.0 mL  =  0.0500 L

 

                                   

 

                                                [H+]   =  0.00010 moles   =    0.0020 M

                                                                  0.0500 L

                                               

                                                pH  =  1.70 M

 

 

 

 

 

 

 

 

 

6.         a)         Write the balanced equation representing the reaction of HF with H2O.

 

                        HF  +  H2O   D  H3O+  +  F-

 

            b)         Identify the Bronsted-Lowry bases in the above equation.

 

 

                        H2O    and      F-

 

 

7.         Consider the following data:

 

            Barbituric acid                        HC4H3N2O3                 Ka  =  9.8  x  10-5

            Sodium propanoate     NaC3H5O2                    Kb  =  7.5  x  10-10

            Propanoic acid                        HC3H5O2                     Ka  =  ?

 

            Which is the stronger acid, propanoic acid or babituric acid? Explain using calculations.

 

            Ka (HC4H3N2O3)  =                           Kw                              =          1.0  x  10-14     =            1.3  x  10-5

                                                            Kb(C3H5O2-)                          7.5  x  10-10

 

 

            Barbituric acid is a stronger acid because it has a larger Ka.

 

 

8.         A solution of 0.0100 M lactic acid, HC3H5O3, has a pH of 2.95. Calculate the Ka value. 

 

                        HC3H5O3                    D                    H+                    +                      C3H5O3-

 

            I           0.0100 M                                            0                                              0

            C         0.001122                                             0.001122                                 0.001122

            E         0.008878                                             0.001122                                 0.001122

 

 

            Ka       =          (0.001122)2     =          1.4  x  10-4

                                     0.008878

 

 

9.         a)         Write equations showing the amphiprotic nature of water as it reacts with HCO3-.

 

                        HCO3-    +   H2O   D    H3O+   +  CO32-

 

                        HCO3-    +   H2O   D    H2CO3   +  OH-

 

 

            b)         Calculate the Kb for HCO3-.

 

                                    Kb (HCO3-)  =                        Kw                              =          1.0  x  10-14         =          2.3  x  10-8

                                                                                    Ka(H2CO3)                             4.3  x  10-7

 

 

 

 

 

10.       Calculate the [H3O+] in 0.550 M C6H5COOH.

 

 

 

                                    C6H5COOH               D                    H+                    +              C6H5COO-

 

                        I           0.550 M                                              0                                  0

                        C         x                                                          x                                  x

                        E         0.550  -  x                                            x                                  x

           

           

                                                               0       small Ka approximation

 

                        (x)2                  =                      6.5  x  10-5

                        0.550

 

 

                        x          =          [H3O+]            =          6.0  x  10-3 M