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AP Chemistry help, and preparation for AP test.

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Books [24 Oct 2006|10:49pm]

palleresen
Hello!
AP Chem is the toughest class in my schedule right now, and I'm suffering with its tests. Our teacher gives us a lot of questions from the AP exam.

I am wondering if you could recommend some helpful guide books. Specifically, I'm looking for those that offer easy-to-understand explanations and tips for tackling various questions.

Thank you!!!
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[24 Sep 2006|05:35pm]

depphead
Alright, the problem I'm working on says:
"Balance the flollowing oxidation-reduction reaction that occurs in acidic solution using the half-raction method."

Cu(s) + NO3-(aq) ---> Cu2+ + NO(g)

What I have so far for the charges they have are for the left side:
Cu = 0
O = -2

and for the right side:
Cu = +2
N = +2
O= -2

What would N be on the left side? And are the other ones right?

x-posted
5 comments|post comment

[18 Sep 2006|04:31pm]

depphead
I'm so not getting precipitates. We just learned them in class today and our teacher did a horrible job of explaining. My homework is:

When the following solutions are mixed together, what precipitate (if any) will form?
a.) FeSO4(aq) + KCl(aq)
b.) Al(NO3)3(aq) + Ba(OH)2(aq)
c.) CaCl2(aq) + Na2SO4(aq)
d.) K2S(aq) + Ni(NO3)2(aq)

For the reactions in the above exercise, write the balanced molecular equation, complete ionic equation, and net ionic equation.

Any help?
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AP Chemistry Book [01 Sep 2006|10:08pm]

unstableharmony

Hi everyone.

I’m in college; my first year and I’ll be taking general chemistry for the entire year (general chemistry I&II). I need it for my degree requirements and my future grad school requirements as well. I didn’t take AP Chemistry; but I thought AP chemistry review books should be able to help in general chemistry classes for college right?  

So what are your favorite chemistry review books?

I have been told that 5 Steps To A 5 and Barrons are awesome. Any others?

Thanks so much!

X-posted.

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[28 Aug 2006|05:35pm]

depphead
I need explaination of how to do the following problem:

How many Fe atoms and how many moles of Fe atoms are in 500.0g of iron?

Any help is appreciated. x-posted.
3 comments|post comment

Nuclear and other Chemistry [23 Apr 2006|07:41pm]

jemixe
Hello, I'm a chemistry student, whose teacher is really smart, but alas, Russian. Her english is good, but her explanations are a bit lacking. Any, my book was written by a bunck of Doctors who assume the students can decode their words, without a decoder ring.

So, I basically have a few questions that I could use some help with.

1) How exactally does one find the coordination number and oxidation number of a metal? For example, [PtCl4(en)]? My book doesn't say much on how to find the coordination number.

2)And, I have a question pertaining to radiation and a lab-rat. Suppose a rat is Xgrams, and is exposed to radiation for Xseconds, absorbing 65% of emitted alpha particles, each having energy of 9.2 x 10 to the -13 Joules. What is the absorbed dose in millirads and grays. (X in the above question is arbitrary. I don't want the answer to my homework, only how to find the answer, ergo, the X's.)

3)Where can I go to find out how to draw geometric isomers? My book is vaque. And how and one formula have two different geometric isomers?

4)Half-life? The half-life for the process of Uranium-238 to Lead-206 is 4.5 x 10 to the 9. A mineral sample contains 75 mg of Uranium-238 and 21 mg of Lead-206. What is the age of the mineral? I found an example that would work if I knew the original amount of each element, not what's left.

That's it. Any clarification that anyone can give me will be whole heartedly appreciated. Virtual cookies will flow freely, and lots of XXXXX's. Thanks.
4 comments|post comment

[09 Apr 2006|10:15pm]

funnyflower
howdy. i was wondering if anyone knows good internet sites that'll help prep for the chem exam
1 comment|post comment

Update [29 Mar 2006|10:22pm]

unheiligengel
Are ya'll ALIVE?

We're just about done with electrochemistry and redox. Only thing we have left to do.

Where is everyone, and what do ya'll need help with? I have old old AP chemistry problems if anyone needs them for a certain subject.
5 comments|post comment

'yo. This allowed? [09 Dec 2005|10:32pm]

unheiligengel
Alright, my teacher is super strict and gung ho about the test, so he made us a cd with old practice problems and some free response from the actual AP test.

I'd like to know where everyone is. We just finished Kinetics, and I have an independant study chapter on Orgo coming up.

If I know where everyone is, then I'll be able to post relevate problems and not ones that are two, three, four chapters ahead of everyone.
4 comments|post comment

[23 Nov 2005|03:09pm]

deprivedspirit
[ mood | hopeful ]

Hey,

I'm new to this community.

I was wondering if anyone could tell me another way of finding the molecular structure of molecules a different way than my teacher showed us, (We just guessed and checked pretty much) or is that really the only way to figure it out?

Thank you!

4 comments|post comment

Okay, so..when is studying supposed to pay off? [11 Nov 2005|11:11pm]

unheiligengel
I hope there isn't too many rules against ranting in here.

But I got an 85 on my last chem test, curved. I'm not quite sure what the raw score was, but the highest raw score was a 75, the second highest a 50, and most people got 20's or 30's.

...now, explain this. I did all the homework problems. I got them all right. I explained them to the salutaritorian next to me, who still didn't understand, and still got them wrong. Same with the person who's 3rd in class next to her.

I explain stuff TO THE BLOODY TEACHER.

After grading the tests, he accuses us of being lazy lil slackards who dont' care about chemistry and don't understand basic simple concepts. Now, tell me how, if I went over all my questions, and I understood the answer for every one, and why it was so, and got all the homework right, why did half the class do better than me, when they couldn't explain how to get molality?

I want it to make sense, because apparently honesty, diligence, studying, and hardwork aren't paying off.
Oh, I understand, I'm just not making the grades to say I understand.

I hope I do better on the AP test.

In other news, we just finished Colligative Properties. Where are ya'll at?
4 comments|post comment

what you need from this chapter before moving onto oxidation reduction shiz [16 Oct 2005|05:14pm]

ffdoh
if you can do this, i reccomend moving onto the oxidation-reduction stuff.

20 cubic centimeters of 2M Sulfuric Acid(aq) + 15ml of 3M Sodium Hydroxide(aq) = Sodium Sulfate and Water

how many grams of water will this create? Will the sodium sulfate precipitate out of the solution as a solid? If so, use the yeild of water to calculate how many grams of this salt will form.

If you need to review or need hints, they are below:
1. Sulfuric acid is aqueous hydrogen sulfate.
2. Sulfuric acid is a polyprotic acid yeilding two hydrogen ions, and is a strong electrolyte, sodium hydroxide is also a strong electrolyte, thus they both ionize(disassociate) completely in water.
3. Molarity= moles of solute per liter of solution
4 comments|post comment

chemmy goodnez [12 Oct 2005|05:28pm]

ffdoh
attention norhoff peeps:

if we truly wish to prepare for the ap test, we must have finished through chapter 22 by april, and Nakao reccomends doing so by spring break, as to have time for review. At the current pace of the class, by april we'll be on like... chapter 12 or something. This is probably a good thing, since many people in the class did not want to take the true AP class.

Thus, i and those who want to at least make a concerted effort to pass the AP exam must complete chapters at a rate of a little more than one for every two weeks. To do so would be an astonishing accomplishment; giving us college credits, massive respect form Sidhu and Nakao, most likely a jaw-dropping amount of extra credit, and the ultimate knowledge that we TRULY EARNED the extra grade point...

What i need to know is whether any of you want to join me, and turn this community into an online course, turn weekend time into study sessions, and turn your mind into a well-greased omnipotent energy being +1, or not.

Because i'm absolutely fine with sitting in my room, late at night, in my underwear, doing calculations on my whiteboards, alone.

good conceptual question that i like, simple, but is the EXACT SAME PROCESS used to determne how one will solve a chemistry problem(unlike memorising percent to mass... blahdeeblah, which is the same as me memorising the tetris song and saying i can play the piano):

A 18 gallon gas tank is refilled at a rate of g gallons per s seconds. How long will it take to be filled?
10 comments|post comment

Atomic radii vs. Ionic radii [05 Oct 2005|10:06pm]

unheiligengel
Stupid LJ ate my last entry.

Alright, so here's my theory on my ionic radii are larger for negative ions and smaller for positive.

Chlorine Ion, Cl-. The balance of protons vs. electrons is upset, and so there's not enough pull on the electrons to keep them in their normal shape, and they wander off to do whatever. Bigger cloud.

Iron III, Fe +3. Once again, balance off. More protons than electrons, so there's a greater pull on the electrons now, and they condense.

...like...number of guards versus number of prisoners.
More guards, a tighter watch.

And all I can understand about the atomic radii, and their size, is that they're the exact opposite.

But I don't understand why, say, Chlorine, the atom, is smaller than Potassium.

Does it have anything to do with shells, and how when the last electron goes into Neon, when that other electron goes into Potassium there's a shield/shell effect, and it's further away?

Or are any of my theories completely off?
6 comments|post comment

[05 Oct 2005|04:20pm]

fishfanatic368
If an aardvark went skydiving and its parachute didn't deploy, would it land on its feet?
4 comments|post comment

yeild methodz [04 Oct 2005|05:35pm]

ffdoh
[ mood | absolutely insane-ane-ane! ]

Hey dudes, and dudettes. Mentioned by some was difficulty in understanding theoretical yeild calculations. I am here to forever lay such concerns to rest forever, banishing them to the fiery pits of... well... you know how in that one movie they imprizoned the guy within the one glass thingy and then flew it into space, and then they did the same thing is that terrible DBZ movie about the tree of life or whatever? It'll be just like that. Can i get an amen?! *awkward silence*

Let's create an imaginary problem, shall we?
100grams Propane (C3H8) combines with excess oxygen to yeild 238.168grams CO2 and a helluvalotta water.
What is the theoretical yeild of CO2? What is the percent yeild?

Stepth:
1. Determine what element, ion, or component can be used to compare two substances with known quantity. This rules oxygen out, as we have no friggin' idea how much we used, and this rules hydrogen out, because "helluvalottawatta" is not a quantitative measurement. Therefore, we will use carbon as our reference, and compare the 100 grams Propane to the 238.168 grams CO2.

2. Here comes the dimensional analysis, the chain of conversions that resembles that little unthreatening can of worms (except watch out when opening it, that lid's sharp) but soon all them worms pile on top of each other to create ONE BIG WORM... and... and KILL YOU with it's WORMLIKE VERACITY!

So anyway, place your 100 grams of propane at left, convert to moles of propane(Molar weight: 44.09652gC3H8/mol), convert to moles of carbon(3mol carbon in 1mol propane), find how many moles of carbon dioxide this can THEORETICALLY create(each mol of carbon can pile two moles of oxygen on it and make one mol of CO2, so it's a one-to-one conversion) and finally, find how much all this CO2 will weigh(molar weight of CO2 is 44. 0098, almost the same as propane, which is just beautiful)

3. VOILA! you now have the weight, in grams of CO2, of your theoretical yeild.

4. Simple. For the percent yeild, divide the yeild provided by the theoretical one you determined. It better be less than 100%. Keep in mind that this percent yeild applies to the entire equation, not just the product you used to calculate it. This percent determines how much of the reaction actually took place, and wasn't lost due a a host of factors such as by sticking to the little spatula thingy.

Okay, so as long as you don;t get sidetracked and start thinking about cans of worms and maybe what would happen if you were in hand-to-hand combat with a coyote, badger, and/or huge-ass pelican, you can use those steps to do any test question on single-reaction yeilds.

Note: a lot of people don;t need to think of individual steps like "well now i'm converting to moles..." etc. whilst doing dimensional analysis. If you are one of these lucky people, ignore the stuff i wrote in the latter half of step two that wasn;t talking about worms. However, if you are like me, make sure you know what your are trying to do and accomplish in your analysis, don;t just start with reactant and end with product. Even though it works, it just... it will fail you inevitably.

If you wanna see how your skillz serve you, try some prolems like pg. 130 #107, or pg. 129 #90.

For all that wondered why i didn;t exlain this BEFORE the test, no one really told me to. Just post to this community with a question like "d00d, how in the bloody hell do i know what the limiting reactant is?" or "in a battle between a beaver and an albatross, which do you think would win?" and i'll "hit dat shit!" so to speak... if by "hit dat shit!" you mean offer assistance in understanding the concepts involved.

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Welcome all! [03 Sep 2005|09:31am]

ffdoh
This is the grand opening of the chemistry community. This place is for those of us that want a little more information, help, or just want some interesting tidbits about chemistry to grace our friends page every once in a while, and for those who wish to post questions or comments about the class. In general it will follow the Honors chem course, but i plan to fill in a few holes when necessary, review if people have trouble recalling things, and later in the year we will surge ahead in order to have a winning "concept toolbox"(analogies are not a gift of mine) for those who wish to take the AP test. In any case, all of this has already been addressed in the bio./rules section of the userinfo.

Current stuff: naming compounds is easy stuff so far, doesn't deserve coverage. What does is the "memorization" of radicals. I suggest first considering the oxygen-bearing ions in this task. They all have the exact same rule! Name=(di or hydrogen at the beginning if it contains hydrogen)+(name of element minus last syllable)+(suffix: ite < ate) If you use this, you will not need to memorize any of those ions, because you will be able to deduce the name, and(excluding some exceptions) the charge on these ions is always negative one.

exceptions and additional easy onesCollapse )

Before i leave, it's also important that we all can do the problems from the previous chapter and no one is left behind. So, make sure you understand how to do this sample problem (pretty much as hard as basic DA gets, you don't actually have to do it if you know you get it) and if anyone can;t do it, it will be explained so we're all on the same level:

The aluminum in a package containing 75 ft2 of kitchen foil weighs approximately 12 oz. Aluminum has a density of 2.70 g/cm3. What is the approximate thickness of the aluminum foil in millimeters? (1 oz = 28.4 g.)

Keep thinking, guys. The key to this is to not take the notes blindly and ignorantly, but interpret them.
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