1. Problem 7-7, Benjamin (2002). Treatment system for degrading acetate. Must do Problem 5-15, parts (a) and (c), also (no need to do part (b) of 5-15). For Problem 7-7, you are asked to consider again the "solution described in part (c)" of Problem 5-15, but there are two solutions in part (c) of 5-15. Use the solution for which the reaction has converted 80% of the HAc to H2CO3, and NaOH has been added.
2. Problem 7-13, Benjamin (2002).
In addition to the question posed in the problem, determine the following first:
(a) TOTCO3 and Alk of the pH 7.3 solution
(mathematically; no log C-pH graph).
(b) TOTCO3 and Alk of the pH 9.5 solution
(graphically).
For problems stating that the solution is in equilibrium with air, or the
atmosphere, use a partial pressure of carbon
dioxide of 10-3.46 bar.
3. In previous years, when I collected
the correct sample from the Big Five Tunnel drainage, we could more meaningfully
analyze the effect of the Big Five Tunnel drainage on the alkalinity of Lefthand
Creek, as we did in Lab 2. Consider this Gran function plot for the
titration of the Big Five Tunnel drainage (50.0 mL sample volume; 0.0012 M H2SO4
titrant):
Here is the alkalinity and pH data for the Big Five Tunnel drainage and Lefthand Creek samples:
| sample | pH | Alk (M) |
| Big Five Tunnel drainage | 3.76 | answer to (a) |
| Lefthand Creek, 40 m upstream | 7.60 | 4.5´10-4 |
| Lefthand Creek, 40 m downstram | 7.40 | 3.6´10-4 |
(b) Using these
alkalinity data, calculate the relative flows of the Lefthand Creek (upstream)
and the Big Five Tunnel Drainage (i.e., determine the ratio QLefthand,up / QBig
Five).
(c) We might expect that Lefthand Creek is in
equilibrium with the atmosphere. With what partial pressure of carbon
dioxide (PCO2, bar) is the Lefthand Creek downstream sample in
equilibrium? Is this a reasonable PCO2 for the Big Five Tunnel
site (consider the elevation).
Last updated on October 07, 2007 at 10:47 PM by Joe Ryan