AP Chemistry 2010 Study thread! Come on people!

<p>Hehehehehe. I didn’t have a table in front of me! I was just trying to think from the top of my head! Whoops ^.^</p>

<p>Yeah it would be. I looked at it wrong at first. He just added wrong for the molar mass.</p>

<p>No, I think I just made up the molar mass of iron ^.^ Wasn’t what I thought it was!!!</p>

<p>Wow thanks a bunch guys! : )</p>

<p>120 grams right?</p>

<p>I am rewatching Death note to relax lol</p>

<p>This is ridiculous…
<a href=“College Board - SAT, AP, College Search and Admission Tools”>College Board - SAT, AP, College Search and Admission Tools;

<p>Look at the solution for 5d!!! It shows Xenon single bonded to the three oxygen molecules! However the most stable structure for XeO3 is Xenon double bonded to them, because the formal charge on each atom is zero! The college board solution is wrong according to the basic rules of VSEPR and also according to Wikipedia! [Xenon</a> trioxide - Wikipedia, the free encyclopedia](<a href=“http://en.wikipedia.org/wiki/Xenon_trioxide]Xenon”>Xenon trioxide - Wikipedia)
And according to this site:
[18</a> - Macksasitorn - Noble gases - Confluence](<a href=“http://wikis.lawrence.edu/display/CHEM/18+-++Macksasitorn+-+Noble+gases]18”>http://wikis.lawrence.edu/display/CHEM/18+-++Macksasitorn+-+Noble+gases)</p>

<p>Would I lose points for drawing the correct Lewis structure on the AP Exam??? It does not even provide this structure as an alternate, it only provides the <em>completely incorrect</em> single-bond structure as a solution. This is totally ridiculous! Somebody explain what’s going on here??</p>

<p>2NH3–>NH4+ +NH2-</p>

<ol>
<li>In liquid ammonia, the reaction represented above occurs. In the reaction, NH4+ acts as
a. A catalyst
b. Both an acid and a base
c. The conjugate acid of NH3
d. The reducing agent
e. The oxidizing agent</li>
</ol>

<p>I think it’s c</p>

<p>a. i don’t think so. It’s not consumed or anything
b. NH4+ is an acid. It’s not amphoteric (such as HSO4(-) because it can accept an H+ to become H2SO4 or donate its H+)
c. NH4 IS the conjugate acid of NH3 because they differ by 1 H+ ion
d. not a redox rxn
e. not a redox rxn</p>

<p>it should be C because it is the conjugate acid of NH3 </p>

<p>& bob i replied in your main thread, the lewis dot diagram you suggested should be a better alternative to their answer… not sure why they put theirs</p>

<p>bobtheboy yea that is an error.</p>

<p>I think the answer to 22 is c???</p>

<p>Just realized I have some basic mathematical deficiencies! well…with calculator in hand at least</p>

<p>Can someone tell me how exactly in the calculator I would type in 4 square roots of something, the only buttons I can find are sq. root and cubic sq. root.</p>

<p>For example, in a Ksp problem I took Ksp value and turned it into algebraic form according to the expression:</p>

<p>3.2 x 10^-9 = (3x)^3(x) = 27x^4</p>

<p>Now when I go to set it up I have 3.2 x 10^-9/27 sq. roots of FOUR. How do I even type that in so I can solve?</p>

<p>^^</p>

<p>((3.2 x 10^(-9))/27)^(1/4)</p>

<p>1/n power is n root</p>

<p>thanks for clearing that up : D</p>

<p>on second look, xe 's oxidation state is +6, so I believe their lewis structure is correct. But, I would hope they’d give partial credit for double bonds…</p>

<p>in the single-bonded lewis diagram, Xe has a charge of +3 and the O(s) have a charge of -1. This gives the molecule a formal charge of 0. (3+ -1 + -1 + -1 = 0). While the other diagram also has a formal charge, xenon would have 14 valence electrons which would make it incredible unstable. The single-bonded version gives it 8 valence electrons.</p>

<p>OK I’ve been digging up some dirt on what may show up on part A of the frq tomorrow. It has to be an equilibrium problem, and it can be one of 4 types: acid-base, buffer, gaseous, or precipitation</p>

<p>I think I may have caught on to a trend…unless you guys think CB would have the audacity to break it?</p>

<p>Part A of FRQ past yrs. </p>

<p>2006- precipitation
2007- acid-base
2008- gaseous
2009- buffer
2010- precipitation??</p>

<p>haha you mean Q<ksp, q=“Ksp,”>Ksp?</ksp,></p>

<p>[YouTube</a> - The Solubility Rules Song](<a href=“http://www.youtube.com/watch?v=CFc0Oe1DUaw]YouTube”>http://www.youtube.com/watch?v=CFc0Oe1DUaw)</p>

<p>If it’s Ksp, I better start studying… I didn’t really get that part in class… buh.</p>

<p>haha yup the solubility product problems. that’s actually the only type of equilibria i’m confident with…let’s hope for it. </p>

<p>Went back further with the frq trends though…no correlation. Nevertheless, CB officials may notice “hey, we haven’t thrown down a Ksp problem in a while. lets do that.” </p>

<p>Just don’t expect buffer equilibrium since that was most recent to show up.</p>