<p>Hmmm, good question lol.</p>
<p>H2SO4 H2O, i’d say</p>
<p>draw each structure first. then decide.</p>
<p>wait no
C6H14 C8H18?</p>
<p>i dont even know if im thinking about this correctly…</p>
<p>well, i know this has to do with raoults law: pressure times mole fraction of solvent.</p>
<p>and it only works with two substances that are totally soluble right? Like they have to obey the ‘‘like dissolves like’’ rule?</p>
<p>ahhhh! lol. tell me!!!</p>
<p>i wanna know…and i gotta go eat :)</p>
<p>it’s the one with the alkanes. So you’re right.</p>
<p>hey, here’s an actual AP FR our teacher had us do. Can u explain part C to me (preferably thru “RICE” method). Cuz my teacher can’t (yea, i’ve dealt with this all year, and have taught myself this class to me all year):</p>
<p>CH3NH2 + H20 — CH3NH3+ + OH-
Kb=5.25 x 10^-4
part a) get OH- concentration of .225 M methylammonine solution
part b) get pH if .01 mole of CH3NH3+ is added to 120. mL of .225 M methylamine (no volume change)</p>
<p>part c!!) how many moles of HCl or NaOH should be added to get solution in part B to pH of 11? (no volume change)</p>
<p>part d) 100 Ml of water is added, how does it affect pH?</p>
<p>This is prob easy for you guys, but I am so unclear on the concept of chemistry. My teacher doens’t understand it, has trouble with math, but always resorts to plain math to show whats happening. gah!</p>
<p>One organic chem text as well as internet resources all say Van der Waals = LDF.</p>
<p>Your textbook must be old, here’s a page about LDF <a href=“http://en.wikipedia.org/wiki/Van_der_Waals_force[/url]”>http://en.wikipedia.org/wiki/Van_der_Waals_force</a></p>
<p>Why is ice less dense than water?</p>
<p>as it freezes, water sort of expands. the stalled hydrogen bonds contribute a lot to the expansion</p>
<p>And a phase diagram shows a negative solid-liquid line.</p>
<p>According to General Chemistry by Petrucci (1999), a widely used text, Van der waals forceS include LDF and Dipole-dipole.</p>
<p><a href=“http://www.chemguide.co.uk/atoms/bonding/vdw.html[/url]”>http://www.chemguide.co.uk/atoms/bonding/vdw.html</a></p>
<p>Check out that page. Looks more official than wikipedia.</p>
<p>Quote from page: “Dispersion forces (one of the two types of van der Waals force we are dealing with on this page) are also known as “London forces” (named after Fritz London who first suggested how they might arise).”</p>
<p>Yes LDFs are part of it, but not all.
van der Waals forces: dipole-dipole interactions.</p>
<p>But ah chah!! Big finding here. This could be where you are coming from. This might raise some controversery: Quote from sight:</p>
<p>"Warning! There’s a bit of a problem here with modern A’level syllabuses. The majority of the syllabuses talk as if dipole-dipole interactions were quite distinct from van der Waals forces. Such a syllabus will talk about van der Waals forces (meaning dispersion forces) and, separately, dipole-dipole interactions.</p>
<p>All intermolecular attractions are known collectively as van der Waals forces. The various different types were first explained by different people at different times. Dispersion forces, for example, were described by London in 1930; dipole-dipole interactions by Keesom in 1912.</p>
<p>This oddity in the syllabuses doesn’t matter in the least as far as understanding is concerned - but you obviously must know what your particular examiners mean by the terms they use in the questions. Check your syllabus.</p>
<p>If you don’t have a copy of your syllabus follow this link to find out how to get one. "</p>
<p>Should we pursue this ‘‘syllabus’’ concern?</p>
<p>And I think all intermolecular forces are Van der waals BECAUSE of Van der waals Gas equation, which allows for the calculation of gases that deviate from the ideal gas law. And while we are on the topic of this equation, have you guys ever had to use it? I have just used PV=nRT…</p>
<p>Water also forms a lattice structure when it freezes, which cause each molecules to be father apart than in liquid state of hydrogen bonding.</p>
<p>Nice explanation…</p>
<p>But about that FR question part c?</p>
<p>which year FRQ was that?</p>
<p>93… is that an innacurate example compared to todays tests?</p>
<p>i wouldnt be surprised if it is… our teacher gave us an 89 MC, which is toally unrealistic, cuz u could use calculators…ahhhhhhhh, what the heck is he thinking??? why would he do that??</p>
<p>My source of textbook is Solomons’ Organic Chemistry text, one of the most widely used Orgo texts around (the others are by Streitwiser sp? and Morrison).</p>
<p>And, the Wikipedia is one of the best reference tools around.</p>
<p>bumping the thread.
what reaction occurs in the sun that allows the sun to have its energy? (Hydrogen fusion)</p>
<p>On the Vand der waals thing: Then does the AP Chemistry guide go by this A Syllabus thing or whatever? Is it important to find out? Because there are a lot of different texts used around the country…</p>
<p>So no one can do part C?</p>
<p>tritium plus deuterium yields He and a neutron</p>