EXAM II
CHM336
10/14/99

This Exam is not intended to be an open book exam, you may consult your text for specific constants, but no more.  You may us class notes as much as you wish.
You are expected to work independently.
This exam is due October 21, 1999 at 11:00am.


1.        Find the concentration of calcium in 2.00 L of water with 1.8 x 10-7M H+ and
            0.10atm CO2 using the following equilibria.

                            CaCO3(s)   <--->    Ca2+(aq)   +   CO32-(aq)       Ksp = 6.0 x 10-9
                            CO2(g)   <--->   CO2(aq)                                      Ksp = 3.4 x 10-2
                 CO2(aq)  +   H2O(l)   <---->    HCO3-(aq)  +   H+(aq)    K1 =  4.4 x 10-7
                             HCO3-(aq)  <---->   H+(aq)  +    CO32-(aq)         K2 = 4.7 x 10-11
 
 

2.        Which of the following metals is more soluble?

            Ba(IO3)2  Ksp = 1.5 x 10-9           or                Ca(IO3)2  Ksp = 7.1 x 10-7
            and
            Tl(IO3)  Ksp = 3.1 x 10-6             or                 Sr(IO3)2  Ksp = 3.3 x 10-7

            Now consider a mixture of all four in a solution with 0.05M NaIO3.
            Calculate the solubility of each metal.

3.        Create a spreadsheet varying the pH from 1-14 and plotting the Zn species
            vs pH using the equilibria below.

            Zn(OH)2(s)  <---->   Zn2+   +  2 OH-                          Ksp = 4.5 x 10-17
            Zn2+   +   OH-   <---->    Zn(OH)+(aq)                       b1  = 2.5 x 104
            Zn(OH)+(aq)    +  2 OH-  <---->   Zn(OH)3-(aq)        b2  = 7.2 x 1015
            Zn(OH)3-(aq)  +   OH-    <---->    Zn(OH)42-(aq)       b3  = 2.8 x 1015

4.        25.00mL of 0.04132 M Hg2(NO3)2 was titrated with 0.05789M KIO3 .
            The solubility product for Hg2(IO3)2 is 1.3 x 10-18 .  Calculate the
            concentration of Hg22+ ion in the solution after the titration of 10.00mL,
            25.00mL, and 38.00mL.

5.        Part One
            Consider Ca(SO4) Ksp= 2.4 x 10-5  Calculate the [Ca2+] in a saturated
            solution.  You must consider ionic strength and solve using an iterative
            method, then find the activity coefficient using the extended Debye-Huckel
            equation.  The ion sizes are:a for Ca2+ = 600  and SO42- = 400

            Part Two
            Use the information in Part One to create a spreadsheet that shows the effect
            of ionic strength on the activity coefficient of both ions.
 

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This document was last modified on Thursday, October 14 1999.