January 2012 | Chemistry

<p>Yes, meatkabob, I remember that one.</p>

<p>I think the question asked what was true of a liquid at its boiling point.</p>

<p>I narrowed it down to B, which said that the number of evaporating molecules equaled the number of those condensing, and C, which said that the atmospheric pressure equals the vapor pressure of the liquid. I'm pretty sure it's C, which is what I put?</p>

<p>I think that takes care of all of the classification questions. Let's move onto the TTCE section. I got 4 TTCES. How many did you all get?</p>

<p>Here's one of those questions I remember.</p>

<p>Water has high surface tension; water has strong intermolecular hydrogen bonds- TTCE?</p>

<p>Here's another T/F type question. :)</p>

<p>At equilibrium, reactant and product concentrations are constant; at equilibrium, no more reactions occur (second part is worded a bit differently)- TF?</p>

<p>I was unsure about that because i thought at equilbrium the rates of reactions are constant and equal....i thought concentration keeps changing but to the eye it seems like it isnt</p>

<p>Yeah, I put C too (the one about pressures)</p>

<p>For Solutions:
Yep, I put Phenolphthalein too (they could have made it a little harder and added some other indicator lol)
And for "Which one releases a gas when combined with acetic acid" I was really unsure too :/ B is probably right now that I think about it... it produces water and CO2 with Acetic Acid right?</p>

<p>Shoot I got 3 TTCE's. Those always mess me up... yeah I remember both of those.
There was one TF about atmospheric pressure? My memory is failing me haha.</p>

<p>Yes ujax, when reactions begin, you have all reactants reacting to form products and no products forming reactants. Then products start reacting to form reactants, and eventually you have equal rates in both directions, hence the concentrations of both the products and reactants stay constant. This proves statement 1 correct. And because they do keep reacting, that disproves statement 2, making the answer T/F, I'm pretty sure.</p>

<p>Hmm... I put TF for the equilibrium one too, because reactant/product amount probably change on a microscopic level but that's just being too technical :P</p>

<p>Oh, I'm going out of order again, but for question 78/79 (one of the last ones) there was a list of acids/bases and like increasing strength? It asked which would occur or something along those lines. I thought the question was kind of strange.</p>

<p>Yes, I remember that one. It asked which reaction was the most effective. You want the reactants in that reaction to be ones that react completely, which are the strongest acids and bases, (the definition of a strong acid/base is an acid/base that ionizes completely in solution) You just had to look at the chart and see which acid was strongest and which base was strongest. Their reaction together would have the greatest product yield, hence the answer, was A, I'm pretty sure.</p>

<p>Which compound is not linear- H2O (it's bent)</p>

<p>Which compound is not polar- CCl4 (the molecule is tetrahedral, and all of the bonds are of equal strength, so the dipoles cancel each other out)</p>

<p>Yep, got H20 and CCl4.</p>

<p>Was there also one comparing radiis of Cl, K, and Na?</p>

<p>Ah I see.
Ok, whew. I momentarily forgot that fact and chose A because I compared all the choices and noticed it was different from the rest. ^^;</p>

<p>Highest Ionization Energy - Argon? (Or one of the noble gases)</p>

<p>Crap, I made a stupid mistake. Unless there was no halogen as a choice, I think I might have chosen a halogen as the answer. I forgot that noble gases have high ionization energies. I thought they had negligible ones, but the negligible thing was their electronegativity. :(</p>

<p>Does anyone know if there was a halogen as a choice for that ionization one? If not, I did choose argon. But now I'm seriously doubting myself. :(</p>

<p>Ah, I forget the choices... I think they were close to Argon though. P, S, Cl, Ar, and... K/Na? One of the metals that wasn't the right one.</p>

<p>Even if you made a stupid mistake, it seems like all your other answers are correct! You're definitely doing better than I am right now :P I think I'm already up to -3/4. 780-790 is my goal now that 800 is impossible blargh. With -1 you'll still have 800 C:</p>

<p>And as a response to your question about K, Cl, and Na:</p>

<p>Cl is a halogen, which have very large radii due to their large number of outer electrons.</p>

<p>K and Na are both alkali metals, which have very small radii. The lower a metal is down a group, the bigger the radius. K is lower, so it has the bigger radius.</p>

<p>Therefore, the answer is Na < K < Cl.</p>

<p>Do you remember if it was atomic radii or ionic radii? I forget but I might have organized it the wrong way because I thought it said atomic -___-</p>

I looked up atomic and ionic radii-
Cl 99pm
Na 154pm
K 196pm</p>

Cl 167pm
Na 116pm
K 152pm</p>

<p>So it looks like if it was atomic, it should be Cl < Na < K and if it was ionic it should be Na < K < Cl?</p>

<p>Let's keep the questions rolling! :) Here's another T/F type one.</p>

<p>Gamma rays are more penetrating than alpha rays; gamma rays have more mass than alpha rays- T/F?</p>

<p>@djumper as you go across a period the atomic radius decreases becoz of increase in the nuclear charge with increased number of protons..hence Na has a larger radius than Cl</p>

<p>@huss182, I think the problem is... was the problem asking for atomic or ionic radii?</p>

<p>@djumper, Yep I got T/F for that one too.</p>

<p>ARG. Just googled and you were right, my reasoning on the size of the halogen atomic radii (and yes, the question asked about atomic radii, unfortunately) was incorrect. So the answer is K > Na > Cl.</p>

<p>So that's 1-2 wrong now with 0 omitted, so 800 is a slim possibility, but I have to hope for a 790 now. I might have to go to a community college. ;)</p>