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<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">The answer in the solutions manual for 17.50(a) end-of-chapter problem is
<br>
incorrect. The Ksp for MZ2 is smaller than the Ksp for MA. The manual does<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">this in terms of “s” (the solubility) and has the wrong formula for the Ksp for MZ2.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Ksp (for MA) = [M][A] = s^2<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Ksp (for MZ2) = [M][Z]^2 = 4 s^3<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">The solutions manual states the later is 4s^2 (which is wrong). It then proceeds<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">to say essentially that 4s^3 has a larger numerical value than s^2. That’s true if<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">“s” is greater than 1. But “s” is given in the question as 4 x 10^-4 M. When you<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">raise a number less than one to a power the result actually gets smaller as the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">power gets larger.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Ksp (for MA) = [M][A] = s^2 = (4 x 10^-4)^2 = 1.6 x 10^-7<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Ksp (for MZ2) = [M][Z]^2 = 4 s^3= 4*(4 x 10^-4)^3 = 2.6 x 10^-10<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">So Ksp (for MZ2) is smaller than Ksp (for MA).<br>
<br>
Dr. Zellmer <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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