Definitive solubility rules for AP Chem, among other quesions.

Test Preparation AP Test Preparation
1

<p>PLEASE correct anything that's wrong; I keep finding conflicting sources. Additional mnemonics (the acronyms I've added) would be appreciated, too.</p>

<p>alkali/ammonium cations: always soluble (preceeds ALL other rules, meaning if something is "always insoluble" the alkali/ammonium salt still is soluble)
nitrate/chlorate/perchlorate/acetate anions: always soluble
halide anions: always soluble except Ag+, Pb2+, Hg2+ (AP/H)
sulfate anion: always soluble except AP/H, Ca2+, Pb2+ Sr2+, Ba2+ (C/PBS)
hydroxide anion: insoluble except Ca2+, Ba2+, Sr2+ (but "slightly"; CBS)
sulfide anion: insoluble except alkaline earth metals
assume everything else is insoluble</p>

<p>Is this correct? Also, should I worry about Beer's law (A = abc) much? I saw it on a random FRQ (2004, I think)...</p>

<p>The MC practice tests from PR and Peterson's seem to involve a LOT of number-crunching - all four operations with 3-4 digit numbers, and of course a calculator isn't allowed for this section. Is the actual exam like this? Any advice?</p>

<p>Bond energies/enthalpy(reaction) seems to confuse me for some reason (I have everything else of thermo- down, though). H(reaction) = sum(bond energies of reactants) - sum(bond energies of products) assuming bond energies are given as positive values, correct?</p>

<p>Something that's always tripped me up (never could get a straight answer from my teacher): when given a compound in solution that is not known to be fully soluble, but no Ksp value (silver sulfate, for example), in a problem such as boiling point elevation, does one go ahead and assume that the compound dissociates into silver and sulfate ions? How about for polyprotic acids? If it doesn't say something like "assume complete dissociation" and also doesn't give a Ka value, then what?</p>

<p>Is there any easy way to remember flame test/ion colors? I'm guessing most people learn these from actually doing labs of this sort, but my teacher didn't have us do any labs for the second half of the course (???). On a side note, will my limited lab experience (probably about 6 or 7 formal labs) be of hindrance?</p>

<p>Dimagnetic/paramagnetic: how does one tell, exactly? </p>

<p>Sorry for all the questions; I know most of my stuff, but I need a 5 to receive credit...</p>

2

<ol>
<li>beer's law is pretty simple and you'd only get it on a FR if ti ever comes.</li>
<li>You've simplified some of the halide rules a little bit. Not too big a deal.</li>
<li>Yes the actual exam is like this. I would practice working with exponents, decimals, and pH's without a calculator if I were you.</li>
<li>Yes, bond enthalpy is the only ever time you use the counter-intuitive reactants - products rather than the usual products - reactants.</li>
<li>Follow the solubility rules for something like AgSO4 so you write it down as broken up</li>
<li>You only break off the H+ for strong acids, but for H2So4 (strong acid), break off only the first H+. Never write weak acids as broken up. Strong acids are HI, HCl, HBr, HNo3, H2SO4, and HClO4 (I'm not sure if HClO4 is one?).</li>
<li>Flame tests requires pure memorization. Perhaps create a mnemonic here as well?</li>
<li>Diamagnetic and paramagnetic are 0-2 questions on the MC. Not-spin-paired means paramagnetic like B2 or O2. Diamagnetic means no unpaired electrons like Be.</li>
</ol>

3

<p>I doubt there will be something on Beer's Law this year, it appeared on the 2003 FRQ and the 2006B FRQ.</p>

<p>delta H=bonds broken - bonds formed</p>

<p>For flame tests, my teacher just said be familiar with them, i.e., know common ones such as Na+, K+, Cu ions, Li+.</p>

<p>Diamagnetic: all electrons paired (dia=two)
Paramagnetic: at least one electron not paired (para=one)</p>

4

<p>Strong acids: (hydro-)bromic, iodic, chloric; perchloric, nitric, sulfuric (BIC PeNS)</p>

<p>Other than that, chloric is the only other acid that might be considered strong (my teacher didn't really give me a conclusive answer on this).</p>

5

<p>so only group 1 and 8 are diamagnetic.
The rest are paramagnetic.
Am I right?</p>

6

<p>bump!!!!!!!</p>