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Quiz 4: Chapter 17 (17.1-17.3)
<br>
<br>
I apologize. I forgot to send this. I did say in class though the
quiz would<br>
cover up through titrations. Thanks to one of your fellow students
for<br>
reminding me.<br>
<br>
<b>Sections 17.1-17.2:
</b><br>
<br>
Common-ion effect and buffer systems. Know what is meant by a CI
effect.
<br>
Buffer systems are just a special type of CI problem. You should be
able to
<br>
recognize when you have a buffer system as compared to a "normal" CI
problem.
<br>
Why? If it's a buffer system you can use the Henderson-Hasselbalch
eqn. to
<br>
calculate the pH of a solution. Remember, to be a buffer you have to
have some
<br>
of each member of a conjugate acid-base pair of a weak acid or weak
base (e.g.
<br>
HF/F-, NH3/NH4+). To be a good buffer system the ratio of the base
component
<br>
to the acid component (or vice versa) should be between 10 and 0.1.
Also, the
<br>
conc. of each component should be relatively large, usually 0.001 M
or larger.
<br>
This has to do with something called buffer capacity, how much
strong acid or
<br>
base can be neutralized ("absorbed") by the buffer so the pH doesn't
change
<br>
much.
<br>
<br>
<b>Section 17.3:
</b><br>
<br>
Acid-base titrations.
<br>
<br>
<b>Homework coverage (you should be able to all problems in the
given ranges):<br>
<br>
</b><br>
For those of you using the 14th edition the quiz covers sections
17.1-17.3<br>
and homework problems 17.1-17.7, 17.13-17.48,
17.83-17.96, 17.110-17.116
<br>
<b><br>
</b>For those of you using the 13th edition the quiz covers sections
17.1-17.3<br>
and homework problems 17.1-17.7, 17.13-17.48,
17.83-17.97, 17.110-17.114
<br>
<br>
For those of you using the 12th edition the quiz covers sections
17.1-17.3,
<br>
and homework problems 17.1-17.7, 17.13-17.48, 17.81-17.95,
17.108-17.112
<br>
<br>
For those of you using the 11th edition the quiz covers sections
17.1-17.3,
<br>
and homework problems 17.1-17.7, 17.13-17.46, 17.75-17.90,
17.102-17.106
<br>
<br>
<b>For the on-line homework:</b><br>
<br>
Do ch 17 homework review problem set. It is due by <b>8 AM
tomorrow</b>.
That<br>
was pointed out in a previous e-mail. Remember there are the DSM
questions<br>
(<b>due by 11:59 PM tonight, I've extended the due date</b>). Also,
there are the<br>
practice exercise #1 problems and tutorial for Ch 17 (neither of
which are for credit).<br>
<br>
On the quiz, if you need to use an ICE table, you must show the work
and the
<br>
ICE table. When making any assumptions you should show that your
assumptions
<br>
are okay (less than 5% error). If the percent error is greater than
5%, you
<br>
need to solve the resulting quadratic equation or use the method of
successive
<br>
approximations (both shown in class and in the notes). You must show
this
<br>
work. If you don't, you will not get full credit.
<br>
<br>
There are 5 links concerning acids and bases on my class web page.
Go to the
<br>
"Helpful Tidbits" link and you will find them at the bottom. These
came about
<br>
from answering e-mail questions from students over the years.
<br>
<br>
<br>
Dr. Zellmer
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