AP Chemistry Review Thread

<p>^^They missed chloride.</p>

<p>a lot more actually,
halides(F-,Cl-,Br-,I-), sulfide(-2), nitrite, thiosulfate(-2) etc.</p>

<p>True, but if you add Cl- to the list, those five are the only ones that have shown up on the AP test since 1981. You're probably safe knowing those five. :-)</p>

<p>How come that when it's a solution, we write it in ionic form?
For example, this one. This is exactly the explanation my teacher gave:
Solutions of manganese(II) sulfate and lead hydroxide are mixed." Therefore, since it is a solution, lead hydroxide is written in ionic form.</p>

<p>I was thinking, why don't we write write it together in the reactants? I thought as a reactant, I would write Mg2+ + SO42- + Pb(OH)2.
But my teacher says for the reactants, it would be:Mg2+ + SO42- + Pb2+ + OH-
I am confused. Why do we break it(lead hydroxide) up?</p>

<p>I don't think you should, I thought Hydroxides were insoluble except for alkali metals and some others (but not lead I don't think)?</p>

<p>You're right and she is wrong. The only strong bases are group 1 and Ca, Sr, Ba.</p>

<p>Ok, that gives me a huge relief.
Thanks a lot guys.</p>

<p>Carbon dioxide is passed over hot, solid sodium oxide
I got CO2 + Na2O --> NaCO3
We don't break up Na and CO3 because it's solid. Right?</p>

<p>You only consider breaking up stuff when they're in an aqueous solution. A gas and a solid is not an aqueous solution.</p>

<p>ok, got it.
I tend to do these correctly. Just making sure I got it down.
Because my teacher had me confused.</p>

<p>does anyone know any websites that have good review notes? i've been barely pulling a "b" all year in my ap chem class, but only because the tests are heavily curved (it's your score out of 100, divided by 2, and add 50 points to it). however, i don't really understand some of the more obscure topics from the beginning that don't really relate to equilibrium. so if anyone knows any good sites, i'd REALLY appreciate it</p>

<p>sparknotes is the only one I know. If you tell me what's bugging you specifically, then maybe I can help you.</p>

<p>I need help with writing complex ion equations.
I just need the general rule and one or two examples.</p>

<p>Like this:
4NH3 + Cu2+--> [Cu(NH3)4]2+</p>

<p>Is this basically what I need to know (besides the exceptions)?
Double the charge of the metal.</p>

<p>Yes, that's the basic rule. That's my worst area as well (I had to self-study that part; out teacher only went over it for literally 20 seconds).</p>

<p>How do you do this problem. It's on the 1994 mc test.
When a 1.00 gram sample of limestone was dissolved in acid, 0.38 gram of CO2 was generated. If the rock contained no carbonate other than CaCO3, what was the percent of CaCO3 by mass in the limestone?</p>

<p>This is how I would do it. I might be wrong, so check with the Chem geniuses here.
CaCO3 ---> CaO + CO2
.38 g CO2, use that to see how many grams of CaCO3 there are.
I got .864327 g.
Divide that my 1 and multiply by 100. so ~86.4%.</p>

<p>yeah, that's the right answer. thanks! i just find it annoying how we don't have calculators for this section and some of the calculations on this practice test im doing are tedious.</p>

<p>Calculators were allowed in 1994 - that's why the numbers are odd. That same question has been rewritten to a noncalculator version:</p>

<p>When a 1.25-gram sample of limestone was dissolved in acid, 0.44 gram of CO2 was generated. If the rock contained no carbonate other than CaCO3, what was the percent of CaCO3 by mass in the limestone? </p>

<p>Much easier!</p>

<p>NP.
Yes, I agree with you on that.</p>

<p>Haha, gfaith explained it.</p>

<p>I need help with paramagnetic. First of all, what does it mean?
and what are some examples of paramagnetic gases.</p>

<p>someone explain dipole dipole and london dispersion. those terms confuse me.</p>