Acids Practice Test 2                        


1.         What colour would 1.0 M HCl be in an indicator mixture consisting of phenol red and thymolphthalein?


            A         red

            B          blue

            C         yellow

            D         colourless


2.         During a titration, what volume of 0.500 M KOH is necessary to completely neutralize 10.0 mL of 2.00 M CH3COOH?


            A         10.0 mL

            B          20.0 mL

            C         25.0 mL

            D         40.0 mL


3.         Which indicator has a Ka = 1.0 x 10-6?


            A         neutral red

            B          thymol blue

            C         thymolpthalein

            D         chlorophenol red


4.         Acid is added to a buffer solution. When equilibrium is reestablished the buffering effect has resulted in [H3O+]


            A         increasing slightly

            B          decreasing slightly

            C         increasing considerably

            D         decreasing considerably


5.         A buffer solution will form when 0.10 M NaF is mixed with an equal volume of


            A         0.10 M HF

            B          0.10 M HCl

            C         0.10 M NaCl

            D         0.10 M NaOH


6.         Which of the following statements applies to 1.0 M NH3(aq) but not to 1.0 M NaOH(aq)?


            A         partially ionizes

            B          neutralizes an acid

            C         has a pH greater than 7

            D         turns bromocresol green from yellow to blue


7.         In which of the following are the reactants favoured?


            A         HNO2   +   CN-      NO2-   +  HCN

            B         H2S   +   HCO3-      HS-   +   H2CO3

            C         H3PO4   +   NH3      H2PO4-   +   NH4+

            D         CH3COOH   +   PO43-      CH3COO-   +   HPO42-


8.         What is the pOH of a solution prepared by adding 0.50 moles of NaOH to prepare 0.50 L of solution?


            A         0.00

            B          0.30

            C         14.00

            D         13.70


9.         What is the [H3O+] in a solution with a pH  =  5.20?


            A         1.4   x   10-14

            B          1.6   x   10-9

            C         6.3   x   10-6

            D         7.1   x   10-1


10.       Consider the following equilibrium: 2H2O(l)   +  energy     H3O+(aq)   +   OH-(aq)

What will cause the pH to increase and the Kw to decrease?


            A         adding a strong acid

            B          adding a strong base

            C         increasing the temperature

            D         decreasing the temperature


11.       The complete neutralization of 15.0 mL of KOH requires 0.0250 moles H2SO4. The [KOH] was


            A         1.50 M

            B          1.67 M

            C         3.33 M

            D         6.67 M


12.       What is the [H3O+] at the equivalence point for the titration between HBr and KOH?

            A         1.0  x  10-9 M

            B         1.0  x  10-7 M

            C         1.0  x  10-5 M

            D         0.0 M


13.       Which of the following would form a buffer solution when equal moles are mixed together?


            A         HCl and NaCl

            B         HCN and NaCN

            C         KNO3 and KOH

            D         Na2SO4 and NaOH


14.       Which of the following acids has the weakest conjugate base?


            A         HIO3

            B          HNO2

            C         H3PO4

            D         CH3COOH


15.       When 10.0 ml of 0.10 M HCl is added to 10.0 mL of water, the concentration of H3O+ in the final solution is


            A         0.010 M

            B         0.050 M

            C         0.10 M

            D         0.20 M


16.       The conjugate base of an acid is produced by


            A         adding a proton to the acid

            B          adding an electron to the acid

            C         removing a proton from the acid

            D         removing an electron from the acid


17.       Which of the following represents the predominant reaction between HCO3- and water?


A         2HCO3-     H2O   +   2CO2

            B         HCO3-   +  H2O      H2CO3    +   OH-

            C         HCO3-   +   H2O         H3O+   +   CO32-

            D         2HCO3-   +   H2O      H3O+   +   CO32-    +    OH-   +   CO2


18.       Water acts as an acid when it reacts with


            I           CN-

            II          NH3

            III        HClO4

            IV        CH3COO-


            A         I and IV only

            B          II and III only

            C         I, II, and IV

            D         II, III, and IV


19.       In a solution of 0.10 M H2SO4, the ions present in order of decreasing concentration are


            A         [H3O+] > [HSO4-] > [SO42-] > [OH-]

B          [H3O+] > [SO42-] > [HSO4-] > [OH-]

C         [OH-] > [SO42-] > [HSO4-] > [H3O+]

D         [SO42-] > [HSO4-] > [OH-] > [H3O+]


20. Which of the following will dissolve in water to produce an acidic solution?


            A         CO2

            B          CaO

            C         MgO

            D         Na2O


21.       Which of the following solutions will have a pH = 1.00?


            I           0.10 M HCl

            II          0.10 M HNO2

            III        0.10 M NaOH


            A         I only

            B          II only

            C         I and II only

            D         I, II, and III


22.       Ka for the acid H2AsO4- is 5.6  x  10-8.  What is the value of the Kb for HAsO42-?


            A         5.6  x  10-22

            B          3.2  x  10-14

            C         1.8  x  10-7

            B          2.4  x  10-4



23.       In a titration, which of the following has a pH = 7.00 at the equivalence point?


            A         NH3 and HNO3

            B         KOH and HCl

            C         NaF and HCl

            D         Ca(OH)2 and CH3COOH


24.       Which of the following salts dissolves to produce a basic solution?


            A         KCl

            B          NH4Br

            C         Fe(NO3)3

            D         LiCH3COO


25.       Calculate the pH in a 0.200 M solution of Sr(OH)2.


            A         1.40

            B          1.70

            C         12.30

            D         13.60


26.       Which of the following solutions has a pH less than 7.00?


            A         NaCl

            B          LiOH

            C         NH4NO3

            D         KCH3COO


27.       Which of the following will form a basic aqueous solution?


            A         HSO3-

            B          HSO4-

            C         HPO42-

            D         HC2O4-


28.       What is the approximate Ka value for the indicator chlorophenol red?


            A         1  x  10-14

            B          1  x  10-8

            C         1  x  10-6

            D         1  x  10-3





29.       What is the approximate pH of the solution formed when 0.040 mol NaOH is added to 2.00 L of 0.020 M HCl?


            A         0.00

            B          1.40

            C         1.70

            D         7.00


30.       In which one of the following equations are the Bronsted acids and bases all correctly identified?




            Acid                 +          Base                         Base     +          Acid


A         H2O2                +          SO32-                        HO2-    +          HSO3-

B          H2O2                +          SO32-                        HSO3-  +          HO2-

C         SO32-                +          H2O2                        HO2-    +          HSO3-

            D         SO32-                +          H2O2                                HSO3-  +          HO2-


31.       Which of the following titrations will always have an equivalence point at a pH > 7.00?


            A         weak acid with a weak base

            B          strong acid with a weak base

            C         weak acid with a strong base

            D         strong acid with a strong base


32.       A buffer solution may contain equal moles of


            A         weak acid and strong base

            B          strong acid and strong base

            C         weak acid and its conjugate base

            D         strong acid and its conjugate base


33.       A gas which is produced by burning coal and also contributes to the formation of acid rain is


            A         H2

            B          O3

            C         SO2

            D         C3H8




34.       Which of the following 1.0 M salt solutions is acidic?


            A         BaS

            B         NH4Cl

            C         Ca(NO3)2

            D         NaCH3COO


35.       Which of the following statements applies to 1.0 M NH3(aq) but not to 1.0 M NaOH(aq)?


            A         partially ionizes

            B          neutralizes and acid

            C         has a pH greater than 7

            D         turns bromcresol green from yellow to blue


36.       When the indicator thymol blue is added to 0.10 M solution of an unknown acid, the solution is red. The acid could be


            A         HF

            B          H2S

            C         HCN

            D         HNO3





1.         Calculate the pH of the solution prepared by mixing 15.0 mL of 0.50 M HCl with 35.0 mL 0.50 M NaOH.



                        HCl                 +                      NaOH                                 NaCl               +          HOH


            0.0150 L  x  0.50 moles                      0.0350 L  x  0.50 moles

                                    L                                                          L


I                       0.0075 moles                          0.0175 moles


C                     0.0075 moles                          0.0075 moles


E                      0                                              0.0010 moles


                                                                        [OH-]   =   0.0010 moles         = 0.20M         

                                                                                                0.050 L


                                                                        pOH    =          0.70


                                                                        pH       =          13.30









2. Calculate the [OH-] in 0.50 M NH3(aq).


                        NH3     +          H2O             NH4+   +          OH-


            I           0.50                                         0                      0         


            C         x                                              x                      x                      Kb(NH3)         =          1.0   x  10-14


            E          0.50  -  x                                  x                      x


                                                0          small Ka approximation                     Kb       =          1.0   x  10-14                 =            1.786  x  10-5

                                                                                                                                                5.6  x  10-10

                                    x2            =       1.786  x  10-5



                                    x          =          [OH-] =          3.0  x  10-3 M             


3.         A titration was performed by adding 0.175 M H2C2O4 to a 25.00 mL sample of NaOH.  The following data was collected.


                                                                                    Trial 1              Trial 2              Trial 3


Final volume of H2C2O4 from burette (mL)                    23.00               39.05               20.95

Initial volume of H2C2O4 from burette (mL)                   4.85                 23.00               5.00

                                                                                    18.15               16.05               15.95                                 average to 16.00 mL



Calculate the [NaOH]                                                                           reject


            H2C2O4            +          2NaOH      Na2C2O4          +          2H20


            0.0160 L                      0.0250 L

            0.175 M                      ? M



            [NaOH]           =          0.0160 L H2C2O4  x  0.175 mole  x    2 mole NaOH

                                                                                      L                    1 mole H2C2O4

                                                                        0.0250 L


                                    =          0.224 M






4.         A 250.0 mL sample of HCl with a pH of 2.000 is completely neutralized with 0.200 M NaOH. What volume of NaOH is required to reach the stoichiometric point.      




            pH  =  2.000    [H+]  =  0.010 M


            HCl                 +          NaOH                     NaCl   +          H2O


            0.2500 L  x  0.0100 mole  x    1moleNaOH  x  L                   =  0.0125 L

                                    L                      1 mole HCl       0.200 mole






5.         If the HCl were titrated with 0.200 M NH3(aq) instead of 0.200 M NaOH, how would the volume of base required to reach the equivalence point compare with the volume calculated in the last question? Explain your answer.


It would be the same

HCl forces the reaction to completion so a weak base is as good as a strong base for neutralizing a strong acid.


6.         Consider the following salt ammonium acetate, NH4CH3COO.

a)         Write the equation for the dissociation of


NH4CH3COO     NH4+       +          CH3COO-



b)         Write the equations for the hydrolysis reactions that occur.



                                                CH3COO-        +          H2O             CH3COOH     +     OH-


                                                NH4+   +          H2O             NH3    +     H3O+


c)         Explain why a solution of NH4CH3COO has a pH =7.00. Support your answer with a calculation.



                        Ka(NH4+)     =   5.6   x  10-10


                        Kb(CH3COO-)            =          Kw                               =          5.6   x  10-10

                                                                        1.8  x  10-5



7.         Consider the following equilibrium:        energy   +  2H2O      H3O+    +    OH-

            a) Explain how pure water can have a pH = 7.30.


                        At a lower temperature the equilibrium shifts left, the [H3O+] decreases and the pH increases.


b) Calculate the value of the Kw for the sample of water with a pH = 7.30.


                        pH = 7.30      [H+]  =   10-7.3    =  5.02  x  10-8 M  


                        remember the [H+]  =  [OH-]  = 5.02  x  10-8 M


                        Kw  =  [H+][OH-]   =   (5.02  x  10-8 M)2     =   2.5  x  10-15