CHM 336
Due 12-14 by 12:15pm.
This is not an open book exam, and you must complete this exam on your own!
1. Since EDTA can be used to find sulfate concentrations,
design an experiment that you would conduct to confirm the amount of sulfate
in the water samples
that you analyzed for your
quant lab project. I want to see specific numbers and a complete
experimental design using the values that you found from the
UV/VIS.
2. a. Describe what is meant by the leveling effect
b. Write
autoprotolysis constant expressions for the following liquids:
H2O
1 x 10-14
C2H5OH
8 x 10-20
H2SO4
1.4 x 10-4
CH3OH
2 x 10-17
NH3
1 x 10-33
HCOOH 6 x 10-7
c. Calculate pCation for each of the above solvents.
4. In anhydrous methanol, the dissociation constant
for acetic acid is 3.0 x 10-10. Calculate
-logCH3OH2+ for a solution
that is:
a. 0.200M in acetic acid
b. 0.100M in acetic acid and 0.200M in sodium acetate
c. 0.200M in sodium acetate
5. Use equation 13-11 in your book to generate
titration curves (pCa2+ versus mL of EDTA added) for the titration
of 10.00mL 1.00mM Ca2+ with 1.00mM
EDTA at pH 5.00, 6.00, 7.00,
8.00, 9.00, and 10.00. Plot all the curves on one graph - be sure
to use enough data to get a smooth curve.
6. Consider the following electrochemical cell;
Ag(s) | AgCl(s) | KCl(aq, saturated) || cell solution
|| Cu(s)
The cell solution was made by mixing 25.00mL of
4.00 mM KCN
25.00mL of 4.00mM KCu(CN)2
25.00mL of 4.00M acid HA with pKa = 9.50
25.0mL KOH solution
The measured voltage was -0.440V. Calculate the molarity of the KOH
solution. Assume that essentially all the copper(I) is in the form
Cu(CN)2-
For the right half-cell, the reaction is Cu(CN)2-
+ e- ---> Cu(s) + 2CN-
(E0 = -0.429 V)
7. Since our last class focused on environmental issues,
describe how you might approach an unknown environmental sample that might
have arrived at your lab.
Define at least five analytes
that are significant environmental contaminants, and describe how you would
use your quantitative skills to measure the levels of
contamination.