**OFFICIAL** AP Chemistry 2013 Thread

Test Preparation AP Test Preparation
141

<p>For potassium, I just think of [P]otassium -> [P]urple (~lilac)</p>

<p>Here’s an easy way to remember the effect of temperature on reaction spontaneity based on enthalpy/entropy change.
If both delta H and delta S are positive, the reaction will be spontaneous at higher temperatures. (think of positive = high)
If both delta H and delta S are negative, the reaction will be spontaneous at lower temperatures. (negative = low)</p>

<p>For remembering which elements can form hydrogen bonds, think of hydrogen bonding is FON. (“fun”, fluorine, oxygen, nitrogen)</p>

142

<p>Copper is blue/green:</p>

<p>If you have ever used PT_Nuke as an antibiotic in a watercooling loop, you’ll know this one.</p>

143

<p>Hey, does anyone know if there might be titration problems on the test? I know there’s at least one equilibrium problem.</p>

144

<p>Excess concentrated hydrochloric acid is added to a 1.0 M solution of cobalt (II) chloride.
How would one approach this?</p>

145

<p>Gibbs Free Energy: AGAHSTAS (Augustus)
→ The A looks like the triangle (=“change”) in the equation, and the middle S stands for subtract</p>

<p>G = (change in enthalpy) - (temperature) x (change in entropy)</p>

<p>G = H - TxS</p>

<p>When G<0, it is spontaneous.</p>

<p>So if H is negative and S is positive, G would have to be negative.
( negative - (positive) = negative)
Likewise, if H is positive and S is negative, G would have to be positive.
( positive - (negative) = positive + positive= positive)</p>

<p>However, when it seems hazy, refer to the equation and more specifically at the temperature. If H is positive and S is positive… then G will be negative when T is large, and positive when T is small. Vice versa when H and S are negative.</p>

146

<p>2 HCl + CoCl2 → [CoCl4]2- + 2 H+.</p>

<p>Kind of reminds me of the synthesis reaction type where</p>

<p>metal ion + hydroxide ion → hydroxo complex ion</p>

<p>e.g. Al3+ + OH- → [Al(OH)4]-</p>

147

<p>But the answer is different o.O
<a href=“http://■■■■■■/2N5Zp.png[/url]”>http://■■■■■■/2N5Zp.png&lt;/a&gt;&lt;/p&gt;

148

<p>I printed this out and it summarizes a lot of the stuff on the exam</p>

<p><a href=“http://www.chemmybear.com/stuff.pdf[/url]”>http://www.chemmybear.com/stuff.pdf&lt;/a&gt;
<a href=“http://www.chemmybear.com/stuff2.pdf[/url]”>http://www.chemmybear.com/stuff2.pdf&lt;/a&gt;&lt;/p&gt;

149

<p><a href=“Supporting Students from Day One to Exam Day – AP Central | College Board”>Supporting Students from Day One to Exam Day – AP Central | College Board;
Questions 1 part d) ii</p>

<p>why is it using hydronium?</p>

<p>would it usually be H+ and not H3O+ ?</p>

150

<p>Maybe a stupid question, but kids in my chem class are saving things into their calculators for part A of the free response (yes that is allowed). Is it worth it to spend some time tonight doing that, or not?</p>

151

<p>What are they saving in them? If they’re the formulas on the formula sheet. Yes, that would be stupid. But if it was say a list of strong or weak acids. I guess that’s ok. </p>

<p>I mean…what would you really need to type in there?</p>

<p>It’d be a waste of time to type formulas and notes into your calculator now. It would’ve been better to do that…say, three months ago. One of my math buddies did that, but it was a while ago and not a waste of time…at the time.</p>

152

<p>A bit off topic but is anyone else also taking the psych exam monday? If so, are you even studying for it or just focusing on chemistry (like me).</p>

153

<p>I have psych too. This morning I’m reviewing some vocab for psych, then I am done. I have consistently gotten above 90% on tests so I really am focusing on chem for the rest of the day-- not that there is much I can do in a few hours.</p>

<p>And I’m relaxing with friends tonight at cinco de Moe’s. We are sick of studying.</p>

154

<p>Last year, I took APES and Psych and by the time Monday rolled around I was completely prepared for Psych so I didn’t worry about. I just looked over a cheat sheet had all the types of Psychology along with the creators and methods.</p>

155

<p>I just hope I can get a 5 on psych with minimal studying because I’m putting all my stress and effort into the chemistry exam. Having them on the same day certainly doesn’t help, either.</p>

156

<p>I just can’t wait to get it over with…definitely going to relax; there’s no use in stressing!</p>

157

<p>Quick question: I instinctively solve the problems without showing work with RICE, and I don’t know when to use it cause it’s completely useless when solving an answer. I’m trying to learn how to show my work using RICE. Will I get credit on equilibrium problems if I forget to use RICE?</p>

158

<p>Do you have to solve the Arhenius equation on the exam…I have not seen iit in any of the past free responses…</p>

159

<p>Same! ^ I was wondering if it’d appear in the MC at all?</p>

160

<p>Maybe you jsut need to know the general idea…eg: use it to find activation energy</p>