Official Chemistry Discussion Topic

<p>Please post all confirmed answers here.</p>

<p>1-4: Laboratory Methods
1. Filtration = separation of liquid from solid
2. Distillation = something about boiling points
3. Chromatography (?)
4. Electrolysis (?)
Unused: Recrystallization</p>

<p>5-9: Element properties
Most stable: Neon
Lowest second ionization energy: Sr
Half-filled d orbital: P</p>

<p>10-12
Gas only: Point C
Gas/liquid: Point D
Solid/gas (sublime): Point E</p>

<p>Synthetic polymer: Nylon</p>

<p>I got 1-5 the same as yours but wasn't it for the lowest 2nd ion. enegry - Ca and for the half-filled d orbital - Cu. though i'm not quite sure for them. i don't remember any Phosphorus in this question. </p>

<p>Polymer - Nylon :-))</p>

<p>how about the Q with how many moles of Al3B4O2 (or something like that) are needed to have 5,60g B?</p>

<p>Thanks.</p>

<p>General comments --- This exam was pretty f'ing hard. I read through the Princeton Review book about 3x, did all the problems after each lesson (and usually missed no more than 1 per section), and still left around 13 blank.</p>

<p>I'm pretty sure Sr has a lower second ion energy than Ca because it's lower on the periodic table, and ionization energy increases as you go from bottom to top, and left to right. Sr also has two valence electrons like Ca does.</p>

<ol>
<li>Fusion</li>
<li>Alpha decay</li>
</ol>

<p>Here are some I had trouble with:
18. Forms oxidation state of +4: ??? (omit)
19. When mixed with soap produces ppt: Ca?
21. Forms blue color when dissolved in sulfate: ??? (omit)</p>

<p>When H ion. energy is decreased from n=2 to n=1, a photon is emitted: True?
The p orbital only holds 2 valence: Definitely true
No CE?</p>

<p>XH3, X = Phosphorus?</p>

<p>To be a polar molecule the shape needs to be t. pyramidal (XH3)?</p>

<p>Balancing equations: Na2O2 + H20 etc. etc. Coeff of O2 = 1? (did in 15 sec)</p>

<p>Which one requires energy input: Formation of H2 gas from two H atoms?</p>

<p>Given [HAc] = 1.8x10^-5M, you can tell it's a weak acid?</p>

<p>What would you not use to measure titrations: balance</p>

<p>More to come.</p>

<p>Re: the 5.60g Boron question</p>

<p>My first thought was 2.00 mol but I didn't answer that one X_X</p>

<ol>
<li>Metals are oxidized when they're mined: True
Oxidation involves removing electrons: True
Incorrect Explanation</li>
</ol>

<p>PV = constant when other vars kept constant (not P sqrt V, P/V, or some odd crap like that)</p>

<p>K(eq) = [aq Prod]/<a href="denom%20had%20Cl-%20to%20the%20fourth%20power">aq Reacts</a></p>

<p>B-L acid/conjugate: H20 was acting as the B-L acid (donated H+ ion)</p>

<ol>
<li><p>Water has a high boiling point for its atm mass: True
Hydrogen bonding is strong: True
Correct explanation</p></li>
<li><p>Answer: London dispersion (weak intermolecular forces)?</p></li>
</ol>

<p>Oops. The one in 5-9 asked for a half-filled p orbital, and that's Phosphorus.</p>

<p>Another one asked for a transition metal (d orbits) with an unpaired electron -- that's Cu (odd atomic #)</p>

<p>you're right about the Sr :o(
16, 17 - teh same :-)
18. wasn't it Carbon, though i don't remember it
19. Ca :)))
21. Cu (not sure)</p>

<p>There is only n=1 in hydrogen so i marked False but the second statement was True</p>

<p>For the polar molecula i guess i marked XH2 like in CO2</p>

<p>coef O2 = 1 :o)</p>

<p>There was another Q about the coef of H20 = 4?!</p>

<p>Energy input: H2--> 2H because it's decomposition :)</p>

<p>The Q with [HA] =1.8x10-5M was it about acetic acid? i guess i marked weak acid.</p>

<p>And Balance is teh right one.</p>

<p>There was another Q about the coef of H20 = 4?!</p>

<p>^ Yes, I got the same thing.</p>

<p>Damn it, I got the decomposition one wrong. Your answer makes sense.</p>

<p>I also left the Boron Q
I have maches for all your other answers except fot the PV. Isn't this the Boyle's Law P/V=const??? </p>

<p>and 56. covalent bonds??</p>

<p>I was thinking about PV=nRT. Since T is kept constant, and nR are obviously constant, PV = a constant.</p>

<ol>
<li>Covalent bonds are much stronger than hydrogen bonds.</li>
</ol>

<p>For the one when T increases from 293K to 393K, PV increases by a factor of between 1 and 2. <3 PV=nRT problems.</p>

<p>For the one with teh T increase, yes i got it the same :)</p>

<p>But 56 i think asked for something more than just the weakest bonds. London forces are typical for inert gases only, so covalent bonds was better answere, though i'm not much sure.</p>

<p>P/V const . - 90% sure Any other opinions??!</p>

<p>i guess i got the Q about the polar molecule (XH3) wrong :o( you're right about it</p>

<p>how many TT CE did you have? I had 4.</p>

<p>I only had 3 TTCE's but that was the one section on the test where I think I took a big hit. For 56 I put hydrogen bonds I think (but that's just me), but I thought it asked about strongest bonds, oh well I guess I misread.</p>

<p>What did everyone put for the greenhouse CO2 problem? I put T T (incorrect explanation).</p>

<p>And there was that one roman numeral question toward the end of the test that had Zn ions and stuff in it; I forgot how to do that type of problem (I believe it had Zn ions H20 and something else as choices). I put only the Zn ions would form from the given choices (roman numeral II).</p>

<p>And which ion has a blue sulfate salt?</p>

<p>It's ok... I bombed this test. Everyone did better than me... and by everyone I mean everyone on a nation-wide level, not just CC.</p>

<p>For the greenhouse I'm alsmost absolutely sure it was TT. </p>

<p>As far as 56, I don't remember what it asked for. I just remember that somewhere in the test i marked covalent bonds :)</p>

<p>I put TT for greenhouse...</p>

<p>I can't believe my friend finished the entire test in 20 min. He probably got them all right too knowing him. That was very dishearting.</p>

<p>I guess 101 was TT CE</p>

<p>Yeah I got TT CE for 101 as well, it took me a while to figure out but then it made sense in terms of boiling point elevation, colligative properties, etc.</p>

<p>There was a guestion about 10g of Ar and some N2. And it asked about the liters or teh grams of N2 present. I left it blank. I got 44,8 but there wasn't such an answere. There was 22,4 and 49.</p>