<p>I’m joining this thread!</p>
<p>Is the SAT Chemistry harder or easier than the AP exam ?</p>
<p>The questions are easier, obviously though the curve is much harsher to get the perfect score (~94% vs. ~67%).</p>
<p>Thanks rocker for the detailed explanation 
Here comes another one:
Electrode potentials are:
Zn0 = Zn2+ + 2e- E= +0.76
Au0 = Au3+ + 3e- E= -1.42
If a gold foil were placed om a solution containing zinc ion. the reaction potential would be?</p>
<p>The answer is -2.18 but I think it’s 2.18 
Anyone helps me?</p>
<p>Thanks ;)</p>
<p>I think this is right: Since it’s gold foil, it’s just Au, and it’s the zinc ion so it’s Zn2+. So, the first equation should be switched, and the second is just how it happens. So now the first equation should have -.76 instead of +, -1.46 - 0.76 = -2.18. I hope that’s right/makes sense!</p>
<p>What should we specifically know about organic chemistry (i.e. what needs to be memorized)?</p>
<p>Thanks dancer13, I figured it out :D</p>
<p>Btw, anyone here took practice test 2 (Sparknotes)?</p>
<ol>
<li> The electronic geometry of the ammonia molecule is tetrahedral. BECAUSE Ammonia obeys the octet rule.</li>
</ol>
<p>I chose F T and it’s said that the answer is T T.</p>
<p>What makes me confused is ammonia has tetrahedral geometry???
This contradicts what Barron’s says : ammonia NH3 has trigonal-pyramidal geometry :|</p>
<p>Anyone helps me with this? :(</p>
<p>Thank you :)</p>
<p>The MOLECULAR geometry of ammonia is trigonal pyramidal</p>
<p>The ELECTRON PAIR geometry of ammonia is tetrahedral</p>
<p>Basically molecular geometry only takes into account molecules for structure while electron pair geometry considers nonbonded pairs AND molecules. </p>
<p>Here you can see the molecule is trigonal pyramidal if you ignore the electron pairs
[File:Pyramidal-3D-balls.png</a> - Wikipedia, the free encyclopedia](<a href=“http://en.wikipedia.org/wiki/File:Pyramidal-3D-balls.png]File:Pyramidal-3D-balls.png”>File:Pyramidal-3D-balls.png - Wikipedia)</p>
![http://en.wikipedia.org/wiki/File:Pyramidal-3D-balls.png]File:Pyramidal-3D-balls.png](http://en.wikipedia.org/wiki/File:Pyramidal-3D-balls.png%5DFile:Pyramidal-3D-balls.png){kind=link}
<p>But here if the electron pairs are included in the picture, the molecule is tetrahedral.
[File:Ammonia-dimensions-from-Greenwood&Earnshaw-2D.png</a> - Wikipedia, the free encyclopedia](<a href=“http://en.wikipedia.org/wiki/File:Ammonia-dimensions-from-Greenwood%26Earnshaw-2D.png]File:Ammonia-dimensions-from-Greenwood&Earnshaw-2D.png”>File:Ammonia-dimensions-from-Greenwood&Earnshaw-2D.png - Wikipedia)</p>
![http://en.wikipedia.org/wiki/File:Ammonia-dimensions-from-Greenwood%26Earnshaw-2D.png]File:Ammonia-dimensions-from-Greenwood&Earnshaw-2D.png](http://en.wikipedia.org/wiki/File:Ammonia-dimensions-from-Greenwood%26Earnshaw-2D.png%5DFile:Ammonia-dimensions-from-Greenwood&Earnshaw-2D.png){kind=link}
<p>Note that trigonal pyramidal is just a subset of tetrahedral (another subset is bent, like H2O, where you have 2 nonbonded pairs but you still have 4 areas of electrons surrounding the central atom).</p>
<p>Wow, what an explanation! Thank you
This is the consequence of cramming :(. I must have misread quite a bit of information :|:|:|</p>
<p>Consider the following orderings and decide which of them give(s) a correct trend in ionization energy:</p>
<p>I. Al < Si < P < Cl
II. Be < Mg < Ca < Sr
III. I < Br < Cl < F
IV. Na+ < Mg2+ < Al3+ < Si4+</p>
<pre><code>(A) I only
(B) III only
(C) I and II only
(D) I and IV only
(E) I, III, and IV only
</code></pre>
<p>I chose E because IE decreases as u move down a family => IE must increase as u move up a family => III should be included in the answer :|:|:|
Why the answer is D?</p>
<p>I have the Barrons and PR review book. Which one do you guys recommend?</p>
<p>Study Barron’s if you have the WHOLE week for preparing :). It has more information. Spend around 2 days to read through the books and then review + do practice tests.
If you are pressed for time, use PR. It’s pretty comprehensive.
Good luck ^^</p>
<p>I remember that question, though I can’t say for sure whether it was from sparknotes or barrons. However, I found that too, and I don’t know what to make of it. It should be E. Its probably just a typo.</p>
<p>Yeah I got E as well. </p>
<p>
</p>
<p>At this point, PR.</p>
<p>Correct Explanation
MgCl2 is the correct formula for magnesium chloride BECAUSE chlorine is always diatomic.</p>
<p>I put T F. It’s the right formula, but chlorine isn’t always diatomic (e.g. NaCl). I’m only mentioning chlorine within the context of a compound because that’s how the question presented chlorine, within the context of MgCl2. Obviously by ITSELF chlorine is always diatomic but that’s not how the question is worded. Thoughts?</p>
<p>
</p>
<p>Electroplating generally isn’t spontaneous, and an electric current from an external source is needed to make it happen. Thus, the cell potential would be negative. The reaction is:</p>
<p>2Au3+ + 3Zn0 –> 2Au0 + 3Zn2+</p>
<p>Gold is reduced and zinc is oxidized. </p>
<p>E cell = E reduction - E oxidation
= -1.42 - (+0.76)
= -2.18</p>
<p>If this were to take place in a galvanic cell, one in which there wouldn’t be an external source of electricity, the inverse reaction would take place and the cell potential would be 2.18. This type of thing is beyond the scope of the SAT, and I highly doubt you’ll ever see a question involving a calculation of cell potential on the test. However, it is helpful to know and understand concepts like electroplating, electrolysis of brine, and galvanization. Often, these will help you to answer questions related to descriptive chemistry.</p>
<p>
</p>
<p>Not much. I find that knowing the difference between saturated and unsaturated hydrocarbons is probably the most important thing you need. Other than that, if you have time, study the different functional groups: alcohol, carboxylic acid, ketone, aldehyde, ether, ester, amine, and amine. It’s highly unlikely you’ll ever be asked to identify functional groups in a compound, but you never know. The SAT definitely won’t require knowledge of any others, though. Everything else is far beyond the scope of the SAT.</p>
<p>One last thing: though highly, hiiiighly unlikely, there may be a question on the SAT about orbital hybridization. If there is one, it will almost certainly be based on an organic compound, because hybridization is most evident in carbon.</p>
<p>Thanks rocker, i find it easy to understand your explanation 
Haiz, sparknotes test 3 is discouraging :|:|:|. Do things like components of brass appear on the test?</p>
<p>Yes. That screwed me over on the May SAT.</p>
<p>I think so. I remember thinking there was no way I’d have to know that, and then it came up in May. So know those 5 or so that sparknotes gives you: brass, sterling silver, etc.</p>
<p>Questions: If you have the CB book for all subject tests, can someone explain:
6
13
21,23,24
109
114
34
38 (what is the equation)
42
48
65
Any that can be explained would be greatly appreciated!!!</p>
<p>^^rockermcr-to clarify something, the question asks for the reaction potential. That means it can be both negative or positive. It just happens to be negative in this reaction only because of what’s given: zinc ions and solid gold, meaning that the reaction can only proceed one way. Zinc can only reduce into the metal and gold can only oxidize into ions.</p>