Official Ap Chemistry Fr Discussion

<p>Here it is! Let's talk :)</p>

<p>Ok well on number 1, i don't remember my answers. However, I know methanoic acid was stronger.</p>

<p>I did number 3: Here's a BIG question I have here. For the value of the rate constant, i put 610. I know, when you test the 1 reaction, you get about 611.7. HOWEVER, because of sig figs, i put 610, since the concentrations only had 2 sig figs. I also tested the other reaction, and got answers in the 610'2. SO i don't know, hoefully I'll get credit.
Ln(h2o2) was the answer for the graph, seconds to the minus one, and I THINK the line should be drawn above the first (a slope not as steep).</p>

<p>OK, for 4. Here's what I did:
Zn + Ni2+ --- Zn2+ + Ni
Al(OH)3 + OH- ---- Al(OH)4 -
C2H2 + O2 --- H2O + CO2
Li + N2 --- Li3N
Pb2+ + I- === PbI2</p>

<p>I know everyone is right except the aluminum one (complex ion), although im pretty sure its right.</p>

<p>For 5, i missed the splint one, but diff reactions are supposed to occur.
CaO will be basic, SiO2 neutral, CO2 acidic (H2CO3)
Ag2S is black, 1/3 AgCl will precipitate, sol 1 is Ag NO3, 2 is Na2S, 3 is KC;.</p>

<p>6: C with for bonds to each F
P with five bonds to Fs
S with four bonds to F and one pair of elctrons
bond anlge is 109.5
sp3d for pf5
and seesaw for sf4
4 sigmas, 1 pi
structrue 1 is best (no formal charge)</p>

<p>7: NH3 is hydrogen bonding, NF3 is DIPOLE DIPOLE, difference cuz hydrogen bonding is stronger than dipole
KCl and NaCl is ionic bonding,
NaCl is stronger cuz closer atomic radii</p>

<p>quantum level is 3, shielding is the reason for ion. energies, cuz theres a stronger nuclear pull on the outer electrons as one goes right across periodic table</p>

<p>Cu is element, (for what reason, i said cuz the isotopes weights seem like to average to CU's weight)
62.93 is more abundant cuz of the weighted average concept, it's weight is closer to Cu's weight.</p>

<p>Ok, so that's what i did!</p>

<p>o, if i said ''atomic weight'' instead of ''mass,'' will i be counted against? i wasn't sure which to use.</p>

<p>Did anyone get CH4O as the emperical formula?</p>

<p>Flame tests:
1. NO2 - Flame is turned down. Sometimes there is brown fumes coming out.
2.H2 - Small combustion with a "pop" sound
3.O2- flame rekindles.</p>

<p>tm2000, you are supposed to say atomic weight. Use atomic weight, because you are compiling a weighted average of the different weights. I didn't get that SiO2 would be neutral, I said acidic.</p>

<p>Also, if anyone did question 2, did you get the empirical formula to be C2H2O5, and that the acidity of 2.6 pH was due to a carboxyl group?</p>

<p>I got 2.6 as the pH too.</p>

<p>What? What are you talking about primitivefuture? The problem already said the pH was 2.6. It asked you what functional group was responsible for this. I said carboxyl group, and got C2H2Of as empirical.</p>

<p>Heltahir, I got pH 2.6 too and the carboxyl group</p>

<p>SiO2 is netural, cuz SiO2 has network covalent bonding, it's IMFs are too strong and won't react with water's hydrogen bonds.</p>

<p><a href="http://www.chemguide.co.uk/inorganic/group4/oxides.html%5B/url%5D"&gt;http://www.chemguide.co.uk/inorganic/group4/oxides.html&lt;/a&gt;&lt;/p>

<p>"Silicon dioxide doesn't react with water, because of the difficulty of breaking up the giant covalent structure. "</p>

<p>Its kinda funny that they would give you a combustion reaction for one of the written formulas. Its a free 2 points if you know one of the most basic concepts of chemistry. I also got 2.6 for the pH and put the exact same answer as primitivefuture, minus that it turns brown when exposed to nitrogen. I believe you are correct though. TM2000 I think they might take off a point if you don't mention shielding on 7. Hoping for a 3</p>

<p>other reactions were:
CaCO3 + HC2H3O2 >>> Ca2+ + C2H3O2- + H2O + CO2</p>

<p>BF3 + NH3 >>> F3B:NH3</p>

<p>SO3 + OH- >>> HSO4-</p>

<p>o yeah, I have another question. What were the units on the straight line graph one? I put log(concentration). I also drew a straight line from the starting point, but it had a less steep slope.</p>

<p>I also did the log of concentration. for the graph I actually plotted out all the points :)</p>

<p>i think it was natural log ( ln [H2O2] ) because it says the reaction was first order</p>

<p>umm, i don't think shielding is right. I was looking at answer keys for past FRs very similiar to this, and some actually say shielding is not a correct response. Cl is a common ion for both, so it doesn't matter.</p>

<p>What did everyone get for the empirical formula???</p>

<p>something ridiculous.... i made so many careless mistakes, i am so ****ed</p>

<p>wow, I actually did better than I thought, lol, I actually got some of these answers.</p>

<p>Oh, I did number 8, it was pretty straightforward, I don't remember the order of the questions or my answers though.</p>

<p>and it's natural log: ln(H2O2)</p>

<p>anyone wanna make a guess at the curve? bad, good, or normal?</p>