CHM 112 Ch 13 Practice Problems by stariya

VIEWS: 10 PAGES: 3

									1) Write the formula for the conjugate acid of the following Bronsted bases:
        (a) Br -1    (b) HSO3 -1     (c) C2O4 -2


2) Write the formula for the conjugate base of the following Bronsted acids:
        (a) H2PO4 -1 (b) HC6H6O6 -1 (c) HClO2


3) Identify the two Bronsted acids in the following equilibrium equation:

       HC7H5O2 + NH3                 C7H5O2 -1 + NH4 +1


4) A laundry detergent has a hydroxide ion concentration of 8.55 x 10 -5.
   Find pOH and pH.


5) A Vitamin C solution has a pH of 2.54. Find [H +1] and [OH -1].


6) Complete the following table:

       [H3O+1]       [OH-1]        pH          pOH           Acidic or Basic?

   a) _______        _______       ______      5.85          ___________

   b) 2.9 x 10-4     _______       ______    _______         ___________


7) Write a Ka, acid ionization constant, expression for the ionization of
   pentanoic acid:
                       HC5H9O2 + H2O                H3O +1 + C5H9O2 -1


8) What is the pH of a 0.245 M solution of the strong acid perchloric, HClO4.


9) Using Table 13.2 (p. 359), write the following acids in descending order
(strongest to weakest) of acid strength: nitrous, acetic, carbonic, lactic.
10) Formic acid has a Ka value of 1.9 x 10-4. What is the pH of a 0.050 M solution
of formic acid?


11) The pH of a 0.040 M solution of iodous acid (HIO2) is 2.73. Find Ka for iodous
acid.


12) In a 0.100 M solution of HF, the percent dissociation is 8.1%. Calculate the K a
of HF.


13) Arsenic acid, H3AsO4, is a triprotic acid with Ka1 = 5 x 10-3, Ka2 = 8 x 10-8, and
Ka3 = 6 x 10-10. Calculate the pH of a 0.20 M solution of arsenic acid. Use
approximation technique discussed in class.


14) Hydroxylamine, a base with a formula of H-O-NH2, has a Kb value of
1.1 x 10-8. Find the [H+1], [OH-1], [O-NH2-1], and pH of a 0.20M hydroxylamine
solution.

                        H-O-NH2               H+1 + O-NH2-1

Answers

1)       a) HBr         b) H2SO3              c) HC2O4 -1


2)       a) HPO4 -2     b) C6H6O6 -2          c) ClO2 -1


3)    HC7H5O2 and NH4 +1


4)    pOH = 4.07        pH = 9.93


5)    [H+1] = 2.88 x 10-3      [OH-1] = 3.47 x 10-12


6)    [H3O+1]         [OH-1]           pH          pOH         Acidic or Basic?

     a) 7.08 x 10-9 1.41 x 10-6        8.15       5.85         basic

     b) 2.9 x 10-4    3.4 x 10-11      3.5        10.5         acidic
7)    Ka = [H3O+1] [C5H9O2-1] / [HC5H9O2]


8)    Strong acids completely ionize; pH = -log [0.245] = 0.611


9)    Nitrous, lactic, acetic, carbonic


10)    1.9 x 10-4 = [x][x] / 0.050 ; pH = 2.5


11) K a = [.001862][.001862] / [.03814] = 9.0903 x 10-5 = 9.1 x 10-5


12) K a = [0.0081]2 / 0.0919 = 7.139 x 10-4 = 7.1 x 10-4


13) p H = 1.5 ; only the first ionization needs to be accounted for to approximate


                                                        .
14) Kb = [H+1][O-NH2-1] / [H-O-NH2] ; 1.1 x 10-8 = x x /[0.20]

      [H+1] = [O-NH2-1] = 2.1 x 10-10

      [OH-1] = 4.7 x 10-5      pH = -log[2.1 x 10-10] = 9.7

								
To top