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<div class="moz-cite-prefix">On 07/20/13 10:28, Liza Michael
Klyachkin wrote:<br>
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Okay in chapter 16 problem 72, I don't understand why you have to
subtract 10.88 from 14? You are suppose to find the Kb but that's
a base and 10.88 is the number for a base but 3.12 is for an
acid...when you subtract 10.88 form 14. <br>
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<div>On Jul 20, 2013, at 7:01 AM, Andrew J. Pounds wrote:</div>
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Alright -- here we go. We want to find the <img
style="vertical-align: middle"
src="cid:part1.01080708.00010005@mercer.edu" alt="$K_b$"> for this
weak base (let's call it ZH3).<br>
<br>
<img style="vertical-align: middle"
src="cid:part2.02030708.02070007@mercer.edu" alt="$K_b =
\frac{[ZH_4^+][OH^-]}{[ZH_3]}= \frac{(x)(x)}{0.19-x}$"> <br>
<br>
Now, they gave us the pH -- but we need the OH<sup>-</sup>
concentration to plug in for <img style="vertical-align: middle"
src="cid:part3.07070205.05050701@mercer.edu" alt="$x$">. In the
problem I found the pOH from the pH and then used that to find the
[OH<sup>-</sup>] using the techniques we discussed in class.<br>
<br>
<pre class="moz-signature" cols="72">--
Andrew J. Pounds, Ph.D. (<a class="moz-txt-link-abbreviated" href="mailto:pounds_aj@mercer.edu">pounds_aj@mercer.edu</a>)
Professor of Chemistry and Computer Science
Mercer University, Macon, GA 31207 (478) 301-5627
<a class="moz-txt-link-freetext" href="http://faculty.mercer.edu/pounds_aj">http://faculty.mercer.edu/pounds_aj</a>
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