2010 AP Chemistry Free Response Discussion

<p>@lwxted; that is definitely a 5
i really do not want a 4 after how hard ive worked; do you think ill get a 4?</p>

<p>100.33 raw score (assuming 50 MC… the worst I think I could’ve done.) 5?</p>

<p>I’m not actually too worried about the score. I’m not planning on using the credit since I’m going to major in the general field (I think). It’ll just look nice next to my fives from Comparative Gov’t and Human Geography =)</p>

<p>idk; some people give ranges like 107-160 as a 5, barron’s says 96+ is a 5. princeton review says you could leave half the test blank (raw score 80/160) and still get a 5.</p>

<p>CB doesn’t seem to give a good range of what the ap chem curve is, and they always change the format of the test; people have been giving me ranges of 65-75% correct needed for a 5. Personally, I think its around 67-70%; 75% seems a bit too high. It really depends on how well people did (to a certain extent, because the percentage of people attaining certain scores varies by like 0-4% every year).</p>

<p>here is what I found from another post; I don’t know how reliable it is:
<a href=“http://talk.collegeconfidential.com/ap-tests-preparation/905731-ap-chemistry.html?highlight=chemistry+raw+score[/url]”>http://talk.collegeconfidential.com/ap-tests-preparation/905731-ap-chemistry.html?highlight=chemistry+raw+score&lt;/a&gt;&lt;/p&gt;

<p>does anybody know a reliable cutoff for a 5?</p>

<p>Min. for a 5:</p>

<p>50/75 MC</p>

<p>70% on FRQs</p>

<p>i have a question, i wasnt sure what the question about exo or endo was asking for whether it was to the system or the surroundings, so I just said that since the solution decreased in temperature it would be exothermic to the surroundings. would i get credit for that because they would assume the opposite for the urea?</p>

<p>Question 4a ii is blue because there is more concentration of a base compared to the acid so titrating it beyond the equivalence point would increase the concentration of the base.</p>

<p>Question 6g is the same because E degree cell is not affected by changes in concentration.</p>

<p>I am very sure about this.</p>

<p>Aranstech are you trying to be funny?</p>

<p>Because if you’re not… oh my</p>

<p>The answer is not Zn. It is Zn+2 because Zn has the maximum tendency to lose two electrons to achieve the octet rule. Ionization energy increases as effective nuclear charge increases, which increases as the number of shells occupied by electrons decreases. Therefore, Zn+2 has more ionization energy</p>

<p>That’s correct. Now I don’t even know if that previous post was facetious or just completely wrong.</p>

<p>Wait, are these questions going to be the same for the later test ? which is tomrrow?</p>

<p>in that case, I guess you are referring to the E cell problem. I might as well say that I am not sure but I am sure for the first one. No Joke.</p>

<p>I said it occurs in three step, I think, because the maximum order of reaction is 3</p>

<p>That’s what I though too, because using a cold urea would only decrease the temperature of the solution</p>

<p>Go for it Dillon Jay. I absolutely agree and concur with your assertion. The color is blue.</p>

<p>Hey i wrote that the reaction is unlikely to be a single step because it is unlikely for three molecules to collide in a desired orientation, that is acceptable right?</p>

<p>about what percentage of the raw points do you think will we need for a 5? about 68% ish. That’s what I’m thinking.</p>

<p>Aranstech you are way off. Adding more HCl in a titration makes a solution more acidic. The solution would then be blue. If you start out with more base then acid, then the only way you can cross the equivalence point is by becoming more acidic. Hence acidic. There was .2M KOH and .1M HCL, creating the reaction OH- + H+ –> H20. At the end of the reaction the pH is 13. At the equivalence point there would be .2M of both, and since you are adding more acid, going past the equivalence point would create an acidic solution.</p>

<p>E is dependent on concentration. The short answer to this is because E= E standard - RT/nF natural log(Q). If the concentration is nonstandard, Q is taken into account, which can either increase or decrease E some margin above or below E standard. Concentration does matter in an electrolytic cell.</p>

<p>

No. There can be tenth order reactions. They are just extremely unlikely and no proceed at a perceptible rate. However, it is still possible for them to occur.</p>

<p>when will the official answers come out? My teacher has the calculus ones already…</p>

<p>^ That’s not possible.</p>