Docstoc

CHM 112 Ch 13 Practice Problems

Document Sample
CHM 112 Ch 13 Practice Problems Powered By Docstoc
					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

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:10
posted:11/30/2011
language:English
pages:3