2008 AP Chemistry FRQS up on CB!!

<p>No that was a different question. For one of the Lewis structures it asked for the geometric shape and for the other structure it asked for the hybridization. They were not the same Lewis dot structure.</p>

<p>Can someone explain to me what "partial credit" is on the free response? My teacher never told us how they graded exams (He's actually getting replaced next year due to complaints!) I looked at apcentral for past FR questions and scoring guidelines, and they have it like if you get the answer and show your work, it's 2 points. How do you get partial credit though? Like if you explained something, but it's wrong, do you get like a 1/2 a point?</p>

<p>eeptotheribbit.. its talking about intermolecular forces not intramolecular. It said boiling point. Your kinda off dude.</p>

<p>I think its because Cl2 has more electrons and its london dispersion forces therefore have a greater probability of becoming a stronger dipole than HCl.</p>

<p>"I think its because Cl2 has more electrons and its london dispersion forces therefore have a greater probability of becoming a stronger dipole than HCl."</p>

<p>But HCl is a polar bond, right? And Cl2 would only have London dispersion?</p>

<p>"^^ there hcl would be reduced because the h goes from +1 to 0. I put 2HCl + O2 --> CL2 + 2H20 because the CL goes from a -1 to 0, therefore oxidized."</p>

<p>^^That's definitely not right. H went from +1 to +1 in H2O. Thus it was not oxidized. I asked my teacher and he said the correct product should be HCIO (something). A previous poster mentioned "Metal Chloride + Oxygen Gas = Metal Chlorate". Therefore the product should be HClO3. </p>

<p>I put H+ and ClO3-...I broke it up when it's not suppose to..it's a weak acid...ahhh..Do you think I will get the points off?</p>

<p>So you put HClO -1? I really don't think that's right but w/e. What does everybody else think?</p>

<p>I'm thinking the correct product should be HCIO3 (not broken up since it's a weak acid)</p>

<p>Okay, I checked Linus Pauling's General Chemistry, and according to him,</p>

<p>HCl (g) + 2O2 (g) -> HClO4 (l) dH=-</p>

<p>Jesus thats a hard question.</p>

<p>^^If it's HCIO4, you have to break it up to H+ and ClO4-</p>

<p>That's only if there's liquid water to dissolve it. But there isn't.</p>

<p>On 3c, about the delta S for the reaction, I said it was positive because the reaction was spontaneous (negative delta G and positive E of the cell) and related it to the second law of thermodynamics, which states that spontaneous reactions always result in an increase in entropy (at least I believe that is what it said in my PR book and it makes sense for the most part.)</p>

<p>is this a flawed statement/not decent proof?</p>

<p>well i took my answer from b, knowing that it was spontaneous because delta G is negative, delta S had to be positive to maintain a negative number.</p>

<p>(thats SORT of what I said and it could be wrong)</p>

<p>I said Delta S is positive because the products are more dispersed..</p>

<p>You can have negative delta S and still have a spontaneous according to Gibbs Law</p>

<p>delta G = delta H - (temperature x delta S)</p>

<p>It would be spontaneous at low temperature, assuming delta H is negative</p>

<p>there is a difference between polar BONDS and polar MOLECULES.... CO2 has polar bonds yet is nonpolar.</p>

<p>so if in your explanation you wrote because it has polar bonds it's not right...... (just a statement to some previous posts)</p>

<p>as for the whole delta s thing with the moles thing... if you had 2000000 moles of a pure crystalline solid at 0 degrees, entropy is 0. its not that valid of an argument.... i dont think so at least</p>

<p>stephennn, are you talking about the pyridine solubility one or the HCl vs Cl2 one?</p>

<p>barricade, im just directing it toward the forum because throughout the thread i keep seeing people mention polar bonds, polar bonds, when for the most part they should be talking about the molecules polarity, not the bond polarity.</p>

<p>To the poster on the last page. HCl is a polar molecule even if the H and Cl are held together with a covalent bond or an ionic bond. I am just not sure if its an ionic solid when its with other HCl molecules or held together with dipole dipole forces. Either way, I said the more electrons in Cl2 give the LDF a greater chance of becoming a stronger dipole than HCl.</p>

<p>And I think it is unfortunately HClO3 like I said before. I got it wrong too. And it doesn't matter if its a strong or weak acid because its not even an acid. Its a gas. The whole equation is with gases, that why you don't even break up HCl (strong acid) because its hydrogen chloride gas. I'm retarded though, I broke up HCl for some reason. I wasn't paying attention..</p>