**OFFICIAL** AP Chemistry 2013 Thread

<p>@superstar, by any chance do you go to WJ or BCC? Or maybe Walt Whitman?</p>

<p>@killerskullz</p>

<p>do both hydrogens have to be attached in 6e? if so, why?</p>

<p>yah depends on how well I actually did on the MC too I would be borderline high 4…!!! 2 months…</p>

<p>Reaction 2: “CO2 + H2O = H2CO3”</p>

<p>Are you sure about the product? I wrote this also, but after the exam I remembered hearing that H2CO3 can’t be written like that and needs to be broken up. It clearly can’t be CO2 + H2O, so I thought it would be H+ + CO3-. Do you know if we’d get credit for H2CO3?</p>

<p>Also, my teacher said that only one hydrogen bonds to the oxygen in the last question, and the rest of the H2O molecule just juts out. So I think that part is wrong.</p>

<p>@remembrance, yes they do because methanal has 2 lone pairs and h2o was 2 H’s, so 2 h-bonds would form. whichever number is smaller (number of lone pairs or number of hydrogens) limits the total # of H-bonds, but since the # of lone pairs and the # of H’s are the same, 2 h-bonds form.</p>

<p>How do they base the curve off of? How well people did like SATs?</p>

<p>Am I the only one that found the exam really easy? Maybe it’s because my teacher was really good. But there was nothing I didn’t expect on it besides the calorimetry question which I still did correct.</p>

<p>@collegedreams29</p>

<p>They do the curve after they grade the APs, based on how the scores are. They are done AFTER.</p>

<p>Let’s hope for a good curve :/</p>

<p>Can anyone explain #1Bii please? :/</p>

<p>Did anyone here learn using NMSI??
Or watching NMSI online videos on vimeo with Rene McCormick???</p>

<p>SHE’S THE BEST TEACHER YOU WILL EVER HAVE!!!</p>

<p>Does anyone know what the correct orientation (drawing) is for question 6 with the water molecule and hydrogen bonding? </p>

<p>and I calculated my score on AP pass to be around 122, that should be a 5 right?</p>

<p>@collegedreams29. The dissociation of CaF2 in water is CaF2-> Ca+2 + 2F- right?
so from there, Ksp = <a href="%5BF-%5D%5E2">Ca+2</a> since we know Ksp and [Ca+2], we need to solve for [F-], which I set as ‘x’. Understand?</p>

<p>I drew the hydrogen of water H-bonding to the oxygen of methanal.</p>

<p>At the end of grading, they look at the percentage of each grouped scores. They shift the curve around so half of the population fail (or whatever there percentage is), and meybe 15-20% get fives, fours, and threes.</p>

<p>@caliamy, look in the previous few pages; I uploaded all of the FR answers.</p>

<p>@ethanamide did you connect both hydrogens or only one? Which is correct?</p>

<p>Ah…I’m a borderline 4-5. So nervous. I’m not sure if I did well on the multiple choice. Especially number 2.</p>

<p>[H</a> Bond Acceptors](<a href=“http://employees.csbsju.edu/cschaller/Principles%20Chem/chapter2/2_10_h_bond_acceptors.htm]H”>http://employees.csbsju.edu/cschaller/Principles%20Chem/chapter2/2_10_h_bond_acceptors.htm)
If we look at this link and the second diagram, it seems only one hydrogen per water molecule that hydrogen bonds to a given oxygen in the formaldehyde.</p>

<p>I only connected one hydrogen of water to the oxygen of methanal</p>

<p>EDIT: I actually was going to draw one of the oxygen of water to the hydrogen of methanal, HOWEVER it said in the question to demonstrate A hydrogen bond so i just did the one with one hydrogen</p>

<p>w00t, that’s what I did!</p>