<p>er…did anyone answer lemone’s first Q about knowing what it is w/o drawing them? i want to kno too =[</p>
<p><a href=“College Board - SAT, AP, College Search and Admission Tools”>College Board - SAT, AP, College Search and Admission Tools;
<p>For question 5a, I don’t understand, why isn’t BaSO4 crossed out, how are we suppose to know the color?</p>
<p>Polar - Usually you should be able to tell if it’s polar due to difference in electronegativity.
Dipole-Dipole - If the molecule is polar, then it is dipole dipole
London Dispersion - If it is nonpolar and doesn’t have any H’s bonded to F, N, or O, then it has just london dispersion (NOTE: Most/All compounds have some london dispersion).</p>
<p>Wait, are you allowed to use a calculator during the m/c?</p>
<p>No calculator for the multiple choice.</p>
<p>****…10char</p>
<p>GOOD! The only way to know what colors there are is to memorize the colors of metallic substances when burned, remember the notorious flame test lab?</p>
<p>My teacher said it was about 33% for a 3, 50% for a 4, and 66.7% for a 5. Does anyone want to help me confirm this?</p>
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<p>hmm…bumparoo?</p>
<p>I think I’m basically set for this exam except for some greatly needed review of kinetics and electrochemistry. We barely covered electrochemistry because it was so close to the end. I’ve gotten 5’s on the practice tests so I’m praying I can repeat this on exam day.</p>
<p>First junior in my school to have taken AP Chem as a junior 
Need to prove myself, haha</p>
<p>Make sure you guys know molecular geometries, its a big topic aswell. Trigonal Bypyramidal.</p>
<p>Calculix is right, we are supposed to memorize the colors. </p>
<p>I know that when burned Mn is purple, Cu is blue, Ni is blue-green, Fe is brown, Cro4 is yellow, Zn is colorless, Co is dark red, Br is brown, Cl is green, I is purple. </p>
<p>I dont know about BaSO4 though???</p>
<p>*** we never did that in my class, like ever lol</p>
<p>Oh ya, and another quick point is that it does not matter what the anion is, it is only the cation that decides the color. All Mn compounds will burn purple, regardless of the anion, and all Cu compounds will burn blue regardless of the anion.</p>
<p>Yea. I only know the alkali and alkaline-earth metal colors.</p>
<p>K - Lilac
Li - Crimson
Sr - Orange
Na - Yellow
Ba - Green</p>
<p>EDIT: Here’s a nice solution (haha, no pun intended). </p>
<p><a href=“http://en.wikipedia.org/wiki/Color_of_chemicals[/url]”>http://en.wikipedia.org/wiki/Color_of_chemicals</a></p>
<p>I’m taking US, Euro, and Chem this year, and I had the histories today, so I spent all week studying for those, and really not doing any chem at all… I’ve got a fun, chemistry filled weekend ahead of me!</p>
<p>BUMP to this thread!! ALSO, what are the important points that we need to know for acid/bases, equilibrium, and kinetics? MAN those topics frustrate me!</p>
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<p>Is this just for the flame test?</p>
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<p>This is only true for flame tests right? Because I know that solid [Cr2O7]2- is always orange or something</p>
<p>Anyways, I have a question. Since we don’t have calculators, how would we know what 10^-2.5 is when simplified, for example? I came across a question asking for the concentration of OH- ions when given the pH. I got the answer 10^-2.5, which simplifies to 3.2 x 10^-3, except I don’t know how to get that simplified answer without a calculator and all the answer choices only give the simplified version. Anyone know any tricks? Thanks in advance!</p>
<p>Ocean,</p>
<p>If 10^-2.5 is the pH, the [H+] is 2.5 and the [OH-] is 11.5. Just take the exponent of the pH or pOH if the base is 10. They probably wouldn’t give us one w/out 1x10^, but if they do, the pH has to be within one degree of the exponent. Ex. 3x10^-3 pH =~ [H+] of 3. It would be a little more because of the 3x…so something like 3.3 I would guess.</p>
<p>^ Ohh thank you so much, beta! That makes it a lot easier haha</p>
<p>I just came across another question:</p>
<p>What is the final concentration of barium ions, [Ba2+], in solution when 100 mL of 0.1M BaCl2 is mixed with 100mL of 0.050M H2SO4?</p>
<p>A) 0.00M
B) 0.012M
C) 0.025M
D) 0.075M
E) 0.10M</p>
<p>I keep getting D, 0.075M, but the answer says it’s C…Does anyone know why? Or is the answer wrong…? I basically set up two ICE tables, one for the equation when BaCl2 dissolves and another one for the equation of the reaction between BaCl2 and H2SO4 to form BaSO4. I got 0.01mol of Ba2+ ions formed in equilibrium for the first reaction and I got 0.005mol of Ba2+ ions left in equilibrium for the second equation. I then used c=n/v, with v=0.2L to solve for concentration:</p>
<p>c = 0.015/0.2 = 0.075M</p>
<p>What did I do wrong?
Thanks~</p>