**OFFICIAL** AP Chemistry 2014 Thread

Test Preparation AP Test Preparation
521

<p>Brownster98: Yeah, so you are trying to eventually find some carbonate, XCO3, and it will react with the Sr(NO3)2 to form XNO3 and SrCO3…and so you want to use the Sr(NO3)2 in order to form SrCO3, which will dissolve the least in water since it has the lowest Ksp value, and will therefore precipitate the most. </p>

<p>I think the Princeton review free response questions are good for giving you an idea of the concepts that might be tested, but I agree that the wording sometimes is bad…and there are some things I’ve noticed that I swear are flat out wrong.</p>

522

<p>@PoisonIvy Beer’s Law. A(absorbance) = abc. B is the distance the light travels. C is the concentration, and A is the coefficient. The Absorbance of the solution is proportional to the concentration of the solution</p>

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<p>and are there answer explanations for the collegeboard practice test online @ <a href=“http://media.collegeboard.com/digitalServices/pdf/ap/IN120085263_ChemistryCED_Effective_Fall_2013_lkd.pdf”>http://media.collegeboard.com/digitalServices/pdf/ap/IN120085263_ChemistryCED_Effective_Fall_2013_lkd.pdf&lt;/a&gt; </p>

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<p>For anyone who did the Practice exam for 2013-2014, can you explain FRQ 7? We never learned anything about the relationship between ph and PKa and shifting as we had to rush through the equilibrium unit </p>

525

<p>what % roughly do we need to get right for a 3?</p>

526

<p>@azes15 I had a hard time understanding this concept myself, but think of it with that one equation: pH = pKa + log([A-]/[HA]). So, if pKa > pH, that means log([A-]/[HA]) has to be less than 0, which means that the value of [A-]/[HA] must be less than 1, which finally means that there must be more HA than A-. The opposite is true for if pKa < pH.</p>

<p>So, in summary, if pH < pKa, then the reaction favors the reactant acid HA, and if pH > pKa, then the opposite is true and the reaction favors the creation of the conjugate base A-</p>

527

<p>Ok that makes a lot more sense now! Thank you @geobro10‌ </p>

528

<p>ummmm guys that was weird… I’ll make another one</p>

529

<p>I was banned from the chat room if anyone wants to fix that… -_-</p>

530

<p><a href=“http://tinychat.com/s6dnfs”>Live video chat rooms, simple and easy. - Tinychat; sigh… join this</p>

531

<p>Google Doc for Easier Discussion:
<a href=“https://docs.google.com/document/d/1N4Z4VcY5Woqdk1t99JU0ilzXKL36kzXcLv-JTUC856M/edit?usp=sharing”>https://docs.google.com/document/d/1N4Z4VcY5Woqdk1t99JU0ilzXKL36kzXcLv-JTUC856M/edit?usp=sharing&lt;/a&gt;&lt;/p&gt;

532

<p>What do you think the score would be if I got 60% on both MC and FRQ?</p>

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<p>and are there answer explanations for the collegeboard practice test online @ <a href=“http://media.collegeboard.com/digitalServices/pdf/ap/IN120085263_ChemistryCED_Effective_Fall_2013_lkd.pdf”>http://media.collegeboard.com/digitalServices/pdf/ap/IN120085263_ChemistryCED_Effective_Fall_2013_lkd.pdf&lt;/a&gt;&lt;/p&gt;

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<p>@zah0813 no one knows, since the grading is different than last year’s</p>

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<p>@zah0813‌ I’m guessing that you would get either a 3 or a 4. </p>

536

<p>anyone know how what % I need correct roughly for a 3?</p>

537

<p>the google doc is a fail</p>

538

<p>Honestly, whoever is spamming the doc, just stop</p>

539

<p>just study on your own people…</p>

540

<p>and are there answer explanations for the multiple choice collegeboard practice test online @ <a href=“http://media.collegeboard.com/digitalServices/pdf/ap/IN120085263_ChemistryCED_Effective_Fall_2013_lkd.pdf”>http://media.collegeboard.com/digitalServices/pdf/ap/IN120085263_ChemistryCED_Effective_Fall_2013_lkd.pdf&lt;/a&gt;&lt;/p&gt;

<p>Iam gonna keep asking until someone answers</p>