<p>rd2012, wikipedia has a great list of common colors of ions in solution, salts, and flames.</p>
<p>[Color</a> of chemicals - Wikipedia, the free encyclopedia](<a href=“http://en.wikipedia.org/wiki/Color_of_chemicals]Color”>Color of chemicals - Wikipedia)</p>
<p>This has pretty much everything you need to know, except lead sulfide is brown/black, and titanium dioxide is white.</p>
<p>Hi guys, question - on the free-response part, when writing the 5 equations and answering the questions, if you write the wrong products, but balance it correctly, do you still get the one point for balancing?</p>
<p>@Abrayo: Yes. You get one point for getting the correct reactants, one point for balancing the equation, and two points for getting the correct products.</p>
<p>Hello!
I will be taking AP Chem bext year. To students who use Zumdahl Chemistry, I have a question. Is there any important differences and changes between 7th edition and 8th edition?</p>
<p>Thanks in advance!</p>
<p>^No major differences. Now stop spamming this thread.</p>
<p>@Abrayo: But now there are only 3 reactions to write out (each with a follow-up question).</p>
<p>Question: do you think that if I get around ~70-73% on multiple choice AP practice exams in class and at home that I can get a 5 on the AP Chem test (these were without studying, and without knowing the chem colours)?</p>
<p>most likely</p>
<p>ten char</p>
<p>Does anyone else think it is a little silly that we have 3 classes before our final (which is a mock AP) and my teacher decided to do a lab today instead of start review? We have literally an hour and a half to review the entire course. Plus, she still hasn’t taught us even a little bit of organic.</p>
<p>QUESTION (sorry if it’s already been answered): How much organic and nuclear chemistry stuff will be on the test? We completely skipped nuclear and environmental chemistry, and only went over organic a bit.</p>
<p>Hey guys, I haven’t looked through this whole thread at all yet, so this may have already been answered, buuuut…</p>
<p>Can someone explain to me what significance high polarizability has?
I know that larger atoms have higher polarizabilities, but what does that mean? It’s more easily distorted into a momentary dipole? So what?</p>
<p>Thanks in advance! :)</p>
<p>Higher polarizability means stronger intermolecular forces (dispersion).</p>
<p>Hi guys, I was going through some of the past free-response questions. In particular, this was 2002 Form A.</p>
<p>The answers are explained on a different site, here:
<a href=“http://www2.ucdsb.on.ca/tiss/stretton/CHEM4/sg_chemistry_02_11388.pdf[/url]”>http://www2.ucdsb.on.ca/tiss/stretton/CHEM4/sg_chemistry_02_11388.pdf</a></p>
<p>However, I don’t understand why, for 3c), you divide 243 kJ by the moles of pentane.
I thought you would have had to multiply them, because 243 kJ is how much heat is given off per mole. . . so you would multiply by the number of moles to find the total heat?</p>
<p>Also, it says for the scoring guidelines:
“(Sign required; if units given, they must be correct)”
So basically, if the test does not ask for units and I give incorrect units, I would lose the point?</p>
<p>You divide the kJ by the number of moles because you’re looking for the kJ of the combustion of ONE mole of pentane, so by dividing you end up with the units kJ/mol, which is kJ/ONE mole.</p>
<p>I’m a bit confused on the units, however. It should be kJ mol-1 as deltaH…</p>
<p>Hmm, perhaps they typo-d?
I understand now though, thank you!</p>
<p>In regards to your earlier question, according to Kaplan’s old AP Chemistry book, the 2002 exam had a combined total of 5.3%. (for organic and nuclear stuff).
Nuclear is really easy and simple to get though, so it wouldn’t take long to learn it.
Organic is a little more . . . scattered.</p>
<p>Dear all,
My HS does not offer AP Chem in classroom, so I’m taking it online. I’m worrying about the lab questions on the big test, since I did not learn much about labs through this online course. I’ve learned that the lastest version of AP exam has eliminated specific lab questions in the free response section, but still, do I need to know all of the 22 recommended labs on the CollegeBoard syllabus, or do I just need to know some basic lab procedures/ operations? And what do you think is the best way to review for labs?
Anyone’s help is greatly appreciated =)</p>
<p>I am self-studying, so I don’t know many of the lab procedures either.
I don’t even plan on looking at them much, if they’re not in the free-response.</p>
<p>Another question:
In the free-response section, when writing the chemical equations, do you leave acids as acids, or do you write them as dissociated?</p>
<p>And again: Hydrogen chloride gas is bubbled through a solution of potassium cyanide. It says the answer is:
HCl + CN- = HCN + Cl–
The = represents the arrow.
How come the Cl- isn’t a spectator ion?</p>
<p>
</p>
<p>I took the chem one last year, but you write the species as it predominantly exists (write strong acids in disassociated form). For example, you wouldn’t write HCl as HCl on the products side, since it’s a strong acid. </p>
<p>
</p>
<p>It’s been a while since I’ve looked at chem, but I believe it’s because the Chloride ion (Cl-) is taking part within the reaction (it’s a single replacement). And, notice here, HCN is written as HCN and not disassociated because HCN is a very weak acid.</p>
<p>A spectator ion in this case would the potassium (K+) ion because even though KCl forms on the product side, since KCl is an ionic salt, it disassociates and predominantly exists as K+ and Cl-; since K+ is both on the reactant and product side, we can eliminate it from the net ionic equation. </p>
<p>And, again, it’s been an year or so since I’ve done chem, so someone else might need to confirm this.</p>
<p>
</p>
<p>All you really need to know for organic is basic naming and isomers (cis, trans, stereo) and basic types of organic reactions.</p>
<p>Know how to name ketones, aldehydes, ethers, esters, alkanes, alkynes, alkenes, amines, halides, and alcohols. This might seem like a lot, but it is really just memorization and only takes like 2 days to learn tops.</p>
<p>
</p>
<p>That’s a typo. The correct units are kJ mol-1, since all you are looking for is kJ for 1 mole of pentane.</p>
<p>But then, how come it would be written as H+ Cl- + CN- = HCN + Cl–, since HCl is a strong acid, and then Cl- would be eliminated as a spectator?
Why isn’t it just a synthesis reaction: H+ + CN- = HCN?</p>