CEE 680 18 October 1995
FIRST EXAM
Closed book, one page of notes allowed.
Answer all questions. Please state any additional
assumptions you made, and show all work.
Miscellaneous Information:
R = 1.987 cal/mole°K
Absolute zero = -273{Special Char 176 in Font
"Symbol"}C
1 joule = 0.239 calories
1015 newtons = 1 figanewton
1. (60%) Hypochlorous acid (HOCl, or sometimes written
HClO) is a powerful disinfectant and oxidizing agent.
a. What is the pKa of hypochlorous acid at
1°C?
b. If 10-3F HOCl is added to 1-liter of water, along
with 10-4F Na2HPO4., what is the solution's composition at
25°C?
c. How many moles of NaOH would one have to add to bring
this solution up to pH 9.0?
2. (40%) Mike Switzenbaum has asked you to prepare an
anaerobic reactor feed solution that is buffered at pH 8. The
reactor is to be operated at 25°C. After careful study
you have chosen to use a phosphate buffer.
a. What is the ratio of NaH2PO4 to Na2HPO4 that should
be used?
b. What is the minimum total phosphate concentration
that must be used if the pH is not to deviate from 8 by more
than 0.02 units, when 10-4 F strong acid or base is
added?
c. How many different bow ties does Mike Switzenbaum
own?