EMERGENCY: Chemistry tomorrow!

Test Preparation SAT Subject Test Preparation
1

<p>Well not tomorrow, but the day after tomorrow. </p>

<p>I took AP CHemistry last year and got a 2. I self-studied all year but I don't think I managed to cover all the material (my class hadn't passed not even one student in years.)</p>

<p>Anyway, right afterwards, I took the SAT chem and got a 580.
I am now retaking the SAT Chem (and AP Chem come may) this Saturday. I was initially gonna take Physics and Math 2 and then realized I was better off taking Physics and Chemistry. </p>

<p>I went back to the practice SAT Chem test I took a year ago, and realized how crazy it was. It came from the big College Board Blue book which sucks because it has no explanations for the answers. Anyway.</p>

<p>I need SERIOUS help. </p>

<p>For example:</p>

<p>In section B, how do you solve the questions that they ask, for example:</p>

<p>"If 1 mol of Na2Cro4 and 2 mol of Pb(NO3)2 are mixed with 1 L of water, what do you get?"</p>

<p>And then the answer is "yellow solid and colorless solution" and such. How are you supposed to answer those?</p>

<p>Section A and C Im fine with (mostly.)</p>

<p>????</p>

<p>=/</p>

2

<p>It's an easy one, really.</p>

<p>You have two soluble salts. Sodium Chromate and Lead Nitrate. </p>

<p>Lead, however, is usually insoluble with most things, like Chromate. So, once it sees the Chromate ion chillin' there, it will bond with it and form the precipitate, Lead Chromate which is a yellow solid. Since Chromate was the only thing with color (aside from Lead), the remaining solution (Sodium Nitrate) is colourless so the whole solution is colorless.</p>

<p>Even if you didn't know that Lead Chromate was yellow, you could guess that the Lead would react with the chromate, forming a precipitate and a colorless solution.</p>

3

<p>Memorize the solubility of compounds before the test.
You should know that most lead compounds are insoluable. And Cr compounds are usually in bright colors (mostly yellow or orange, and some green). Sodium compounds are usually white, and solution is usually colorless (think table salt!).</p>