14 October 1992
Open book, open notes.
Answer all questions. Please state any additional assumptions you made, and show all work.
R = 1.987 cal/mole°K
Absolute zero = -273°C
1. (70%) You have an industrial wastewater composed entirely of ammonium sulfide, [(NH4)2S], dissolved in water at a concentration of 0.01 F. In order to explore the possibility of stripping the ammonia and hydrogen sulfide without pH adjustment, determine the complete solution composition (i.e., H+, OH-, NH4+, S-2, and any other species that you suspect might form) at:
You may use a graphical method to help solve this problem. You may ignore corrections due to ionic strength effects.
2. (30%) Sketch a complete titration curve for a solution of 0.005 F Na3PO4 that is titrated with HCl. This should take the form of an xy plot, with pH on the y-axis, and the f or g value on the x-axis. Locate all inflection points first (use a graphical method if you wish) and draw the continuous curve between the points by hand. You may ignore corrections due to ionic strength effects.