<p>Raoult’s Law quantifies the decrease in vapor pressure between a solution and the plain solvent. It only works with ideal solutions, however (where the intermolecular forces between the solute and solvent are similar, and the solute concentration is relatively low).
P=XP°
Where P° is the vapor pressure of the solvent and X is the mole fraction of the solute.</p>
<p>Ohhhh, I like that description of Vapor Pressure. It helped a lot to visualize it that way. Thank you!</p>
<p>This might be a dumb question, but why does adding a solute to a solvent increase the IMF? Dipole-dipole? Or is that completely irrelevant to this particular topic? Haha.</p>
<p>^Pretty much. The more stuff there is in the solution, the more IMF (London Dispersion/Van der waals, Dipole-dipole, etc.) there will be. The fact that there are more particles in the solution leads to more intermolecular forces being present.</p>
<p>Gotcha.
Thanks so much!</p>
<p>List the following compounds in order of increasingly large dipoles?
“HI, HBr, HF, HCl”</p>
<p>I think I just don’t get the concept of dipoles… 
halp?!</p>
<p>Dipoles are based on polarity.
From there, look at the compounds and compare the electronegativities:
F is the most electronegative, so it will have a stronger pull on H’s eletrons, leaving the other side of the H more position. Therefore there is a large dipole.
I is less electronegative and will have a weaker pull, so it will have a smaller dipole (because the electrons won’t be separated as much).
Basically whichever one is more polar has a larger dipole.</p>
<p>I hope that explained it enough?</p>
<p>@Abrayo and skateme</p>
<p>What I don’t like about #73 is the fact that the wording is somewhat vague. Betta- are electrons while Betta+ are positrons (kinda anti-electron). If I knew which test this was from, I’d check the answer myself. In the meantime, I’d stick with A.</p>
<p>@ScholarshipFTW</p>
<p>My explanation isn’t much different than Abrayo’s but I felt the need to toss a few things in: Think of dipoles as the pull of electrons. Depending on electronegativities, one side will have a stronger pull on the electrons than another (note that it won’t always occur). From this pull, the stronger side will be more negative because of the “hogging” of electrons while the weaker side will be more positive. A larger difference in electronegativities (stronger pull on one side) equals a larger dipole.</p>
<p>just read some typos on my last post:
F is the most electronegative, so it will have a stronger pull on H’s eletrons, leaving the other side of the H more POSTIVE, not position. </p>
<p>@chewydog:
I forgot about positrons!
Not sure if they are including that, or just the betas.
You’re right, it is vague.</p>
<p>What’s the bare minimum of points you would need out of the MC and FRQ to obtain a 5 on the AP Chem exam?</p>
<p>^You need 2/3 of the total raw points for a 5</p>
<p>Absolute minimum for a score of 3?</p>
<p>38% for a 3 according to 2002 released exam</p>
<hr>
<p>@Abrayo</p>
<p>Lol, I had to dig all of this out of the dusty corner in my mind. It was a painful sight, I must say, but I’m glad to have refreshed at least two minds on nuclear chemistry.</p>
<p>Although a bit old (2002), I’d estimate this to be a good indicator for “minimum scores” needed. Look on the right side of the first page for the chart of “AP Grade Conversion
Chart: Chemistry”. Yes, bow down and thank my awesomeness. Chocolates, cookies, and mastercards are accepted if a simple bow is not enough to thank me.</p>
<p><a href=“Supporting Students from Day One to Exam Day – AP Central | College Board”>Supporting Students from Day One to Exam Day – AP Central | College Board;
<p>@chewydog: Damn, that’s a harsh curve, and I expect the curve to be a lot harsher this year because of the removal of the guessing penalty.</p>
<p>I’m going to one-up chewydog and post CB’s “revised” curve for 2002 AP Chem: <a href=“Supporting Students from Day One to Exam Day – AP Central | College Board”>Supporting Students from Day One to Exam Day – AP Central | College Board;
<p>I don’t know if CB took out the results from that test and re-crunched the numbers or if they guesstimated, but that’s the “new” curve without guessing penalty.</p>
<p>The new curves for all released exams can be found here: [AP</a> Central - Multiple-Choice Scores](<a href=“Supporting Students from Day One to Exam Day – AP Central | College Board”>Supporting Students from Day One to Exam Day – AP Central | College Board)</p>
<p>My teacher sucks. This is her first year teaching AP and goes easy in teaching because we have kids from regular chem and some who have never even taken chem before. She says that “AP” kids can study on their own for the math problems, etc. I feel like I will fail horribly on the exam, which we all know is in about a week. We haven’t gone through all of the material. On Barron’s 1st diagnostic test, I got a 27/45 raw score on MC. How does that compare to the predicted AP Exam score? Also, I looked at the 2010 FRQ and I have no idea what 85% of the scoring guidelines/questions asked. I am on spring break until Monday, May 2, when I have a Chem test on redox in addition to the AP exam. Not to mention I have a research report due on that day that I haven’t started on for AP Lang. (Lang teacher did not prepare us for the exam either!) How can I balance studying for AP Chem, Lang, and USH this week (given that I have only 1-2 weeks to study), while covering/reviewing the material? Thanks!</p>
<p>@anothergalaxy</p>
<p>You’re going to have to make a choice. If your APUSH class was tough (my school’s is notorious for its harshness to the point where people proudly display their war scars), then you should be prepared for it already and just have read over the review material. I have absolutely no idea about Language though so can’t say much there. AP Chem, from your description, is going to be one of the most difficult for you by far. Whatever major you’re interested in for the future should help you decide. If you’re going for an English major, focus on Language, Science = Chemistry, and History/Law = USH. With about 2 weeks to go, you’re going to have to set priorities. An alternative is to stagger studying a bit depending on test dates. For example, Chemistry is going to be on May 2, which is one of the earliests tests. Focus on studying for that and then branch out from there, but I can’t guarantee success with the second option.</p>
<p>@leadlol</p>
<p>I fear it may be so, which sucks. TT_TT</p>
<p>@314159265 </p>
<p>I accept my defeat, but I still get to have a share in any food/tokens of appreciation people may send :P</p>
<p>Do you guys think it’ll be around 70% for a 5 this year, because of the new policy?
I read somewhere else on here that the change would not affect 5s as much as lower scores, because the people who get 5s normally do well on the multiple choice anyway and random guessing would not benefit them too much. Hopefully that’s true.</p>
<p>@chewydog: Wait. How many points are there in total? Look at the 2008 released scoring guidelines; it’s much different than the ones in 2002. <a href=“Supporting Students from Day One to Exam Day – AP Central | College Board”>Supporting Students from Day One to Exam Day – AP Central | College Board; I know there’s a 50-pt. gap to get a five, but does the number of points change every year?</p>