AP Chemistry





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Discus: SAT/ACT Tests and Test Preparation: May 2003 Archive: AP Chemistry
By Heatwave345 (Heatwave345) on Tuesday, May 13, 2003 - 04:51 am: Edit

ok, today is the big day and i can't sleep..... O_o


gl to all of you taking it and let's keep the discussion here after school.

By Juice (Juice) on Tuesday, May 13, 2003 - 06:02 am: Edit

gl... i expect by 2 EST pm(when i get home) a complete compiled list of answers and questions to be posted ;)

By Coles (Coles) on Tuesday, May 13, 2003 - 07:23 am: Edit

Good luck everyone, only 30 more minutes now.

By Hipstertapioca (Hipstertapioca) on Tuesday, May 13, 2003 - 11:56 am: Edit

i did FR questions 3 and 8, as well as the other assigned ones. honestly can't recall anything. everything is a blur.

By Baseballtwin86 (Baseballtwin86) on Tuesday, May 13, 2003 - 12:21 pm: Edit

I did 2 and 7

I thought it was pretty easy.

By Eurostar (Eurostar) on Tuesday, May 13, 2003 - 01:17 pm: Edit

I did 3 and 7...wow..they actually predicted the spectrophotometer correctly!

By Nutmag345 (Nutmag345) on Tuesday, May 13, 2003 - 01:22 pm: Edit

Does anyone know why water droplets form outside the beaker of an ice bath. Also, why can't the spectrometer not work with Na? I think i can answer your questions on any of the other problems though.

By Hipstertapioca (Hipstertapioca) on Tuesday, May 13, 2003 - 01:42 pm: Edit

water vapor condenses thus forming water droplets, that was the only one that required no thought...is that correct though?

which wavelenght did everyone choose for the spectrophotomer question and why?

for the second balancing, the redox what was the coefficient in front of H+? was it 4? i put 14, because guy next to me put 14...

unfortunatley, i didn't sit next to a very chemistry savvy student so i feel as though someone is out to get me. we were the only 2 non-geniuses in the entire room! ugh. in any case, cheating is bad. ha. okay results july 1st. sat 2 this friday. --

By Baseballtwin86 (Baseballtwin86) on Tuesday, May 13, 2003 - 01:59 pm: Edit

It was 4

Water apor does condense, thermal radiation from the ice bath cools vater vapor in the air and it condenses on the beaker in the bath.

I'm almost positive I got a 5

Equations

Hydrogen Ion + Hydroxide Ion --> Water
Hydrogen Peroxide --> Water + Oxygen Gas
Dinitrogen pentaoxide + Water ---> Hydrogen Ions + Nitrate Ions

Can't remember the others. There was something with Carbonic acid that had to be written out as water and carbon dioxide. And there was an oxidation reduction reaction, where solid turned to ions and ions turned to solid.

Was the one naming in MC 2,4, dimethylhexane?

I was fairly confident in that one.

By Absurdistx (Absurdistx) on Tuesday, May 13, 2003 - 02:18 pm: Edit

I don't want to predict my score, but I dont' want to jinx myself. But let's just say that I was expecting something a lot harder.
2,4, dimethylhexane is what I got.
I got the first two equations with water and water plus oxygen gas the same as you did, but I didn't do the last one. I did the Ag(NH3)4 +2 complext though (plus the Cl-). Did anyone else do that and is that right?
I was so pissed concerning the first FR. Our teacher was saying it would be Ksp or gas equilibrium. I bumped into her in hall this morning and she's like "Oh, this guy on the listserv said it'd be weak base equilibrium. But nah, that's what it was last year."
...
Yeah. So I was a bit miffed at first, but over all - it wasn't too bad of a test.
So why does CH4 not behave like an idea gas?

By Gimix (Gimix) on Tuesday, May 13, 2003 - 02:23 pm: Edit

when you decrease temp and increase pressure, the space between the gas molecules decreases and intermolecular forces become significant...

so under high pressure and low temp conditions, CH4 doesn't behave like an ideal gas.

By Absurdistx (Absurdistx) on Tuesday, May 13, 2003 - 02:30 pm: Edit

Ahh, yes. I cited LDFs on that one...I was thinking there was more to it than that. A kid in my class who was forced to take the test said 'because methane is sluggish.' lol.

By Juice (Juice) on Tuesday, May 13, 2003 - 02:34 pm: Edit

wavelegth was 510... Since that is at its maximum absorbance. Also NaCl doesnt work because its colorless in solution so it wouldn't absorb anything.. thats what i put atleast 2 parts of BEERS law? Concentration and ??? i think one is diameter of curvet but not sure...

By Absurdistx (Absurdistx) on Tuesday, May 13, 2003 - 02:39 pm: Edit

I think got 510, also. Did we have to explain why though? I don't remember it asking.
I think you're right about the reason why NaCl doesn't work...I was stupid and had no idea why, so I put some half-assed answer.

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 02:41 pm: Edit

i put wavelength and concentration for the one asking what you needed to know for beers law =p

oh, by the way, it's actually:

A=ebc

Where A is absorbance (no units, since A = log10 P0 / P )
e is the molar absorbtivity with units of L mol-1 cm-1
b is the path length of the sample - that is, the path length of the cuvette in which the sample is contained. We will express this measurement in centimetres.
c is the concentration of the compound in solution, expressed in mol L-1

taken from http://www.shu.ac.uk/schools/sci/chem/tutorials/molspec/beers1.htm

By Adamg (Adamg) on Tuesday, May 13, 2003 - 02:48 pm: Edit

The MC was harder than the 99 exam but easier than the 88, 84 ones. The spectrometer question was basically an ACT Science type question. Everyone should have done well on that one. The reaction predictions were a joke, even for me who is terrible at them. I did 2 and 8. For that organic question I'm pretty sure it is the hexane because if you draw it out it has 6 main carbons. For the CH4 I said the space decreases so IMFs increase and since temp decreases, the amount of time they are close togeather increases since they are moving slow. For the water, the water molecules bump into the cold surface, lose energy which causes them to phase change into liquid. They form dropplets because of hydrogen bonds between the molecules. What did you guys put on the density of CO2 at 2atm? I can't remember if I put 2 or 4. I either totally f00ked up the first FR or got it entirely correct.

By J_Jay (J_Jay) on Tuesday, May 13, 2003 - 02:48 pm: Edit

the first question was pretty damn hard...as was the fifth but overall i was surprised at how doable it was. The mc was really easy relatively...im just afraid that their might b a bad curve

By Juice (Juice) on Tuesday, May 13, 2003 - 02:49 pm: Edit

I put color and M for beers.. color MIGHT get me credit since it has to do with molar absorbance...

the one with a positron... any1 know that answer... it was N decayed by emitting a positron. I put A.

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 02:50 pm: Edit

well you know @ 2atm there's 11.2L/mol - pressure doubling means the volume is halved.

(44g/mol) / (11.2L/mol) = ~4g/L

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 02:52 pm: Edit

well it was nitrogen 13, so you know that there's 7 protons and 6 neutrons. emiting a positron lowers the charge by one (6 protons) and keeps the atomic weight the same (7 neutrons)

dont remember what the letter was though.

By Juice (Juice) on Tuesday, May 13, 2003 - 02:54 pm: Edit

density of CO2 was 4 im pretty sure just:

Pv = nRT
Pv = g/mm RT
P*MM/(RT) = g/v
(P)(MM)/((R)(T)) = Density
i forget the numbers but that is the setup
(2)(44)/(.08206*280?(i forget the T)) = 3.8 so thats about 4

FR 1)
-----
pH 5.43? whem 5 mls is added.. does that even make sense.. thats what i got any1 else get something similar?

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 02:55 pm: Edit

5.43, i got the exact same thing as did a friend of mine at school.

what did you get for the second pH? 4.67? i dont remember what i put, thought it was 4 something though.

By Juice (Juice) on Tuesday, May 13, 2003 - 02:56 pm: Edit

ppl are posting to fast LOL... yea that was A (for positron)..

By Juice (Juice) on Tuesday, May 13, 2003 - 02:59 pm: Edit

i forget what i got for 2nd ph.. i got 4.67 for something tho... What indicator did u put?

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 03:04 pm: Edit

the one with pK(a) of 3

By Heatwave345 (Heatwave345) on Tuesday, May 13, 2003 - 03:15 pm: Edit

I thought this test was really easy. The only problem that probably will screw me over is the FR acid-base one.

=====================================================
i forget what i got for 2nd ph.. i got 4.67 for something tho... What indicator did u put?
=====================================================

that's what i got and i chose the indicator with pKa of 3.(started with an e)


ok here are my uncertain ones:

MCs:
-What's the chemical you use for baking?
-Molar Mass of 120 g/mol sound familiar?
-the one with precision and accuracy of a student titrating.

FRs:
-Kb of base. something x 10^-10?
-rate law orders? 1,1,2
-Is the silveramine complex Ag(NH3)2+?

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 03:17 pm: Edit

NaHCO3 (baking soda)

what was the molar mass one for? i don't remember the problem.

not enough information to be determined for the precision/accuracy one because you don't know what the correct value was supposed to be so you don't know how accurate his values are

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 03:19 pm: Edit

i don't remember the Kb of the base, but if you got the same pH then you almost definitely had the right Kb =p

yes for those rate law orders.

didnt do that silveramine one, was it a reaction or part of a req. fr?

By Ch2 (Ch2) on Tuesday, May 13, 2003 - 03:20 pm: Edit

do think i can still get a 4 on the AP Chem if i skipped 12 MC (and definitely got some MC wrong) and did fair-OK on the free response??
I messed up so bad on the free response though. but there were somethings i made up, that turned out to be right, so hopefully i got some points..

By 9331 (9331) on Tuesday, May 13, 2003 - 03:21 pm: Edit

how did you explain why acid rain damage buildings?

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 03:22 pm: Edit

you probably can with a 4, the range for 1999 was like 100-160 = 5, 83 - 99 = 4.. something like that although i dont remember exactly.

it's pretty generous. unless you really bombed the free response.

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 03:23 pm: Edit

i said because metal carbonates break down when they come in contact with acids.

then i tried to show the reaction, CaCO3 + HCl (didnt/dont know what acid rain is supposed to be though) --> ... and then i blanked and bs'ed it for the products, think i put CO2 and H2O in there though, at least i hope so :\

By 9331 (9331) on Tuesday, May 13, 2003 - 03:24 pm: Edit

also, when is the earliest time that we can get the free response question?

By Baseballtwin86 (Baseballtwin86) on Tuesday, May 13, 2003 - 03:27 pm: Edit

Fo the weak base free response, I got a pH of 2.97 for the equivalence point. I think I was right because my friend got the same thing. That would mean the indicator would be the one with a pKa of 3.

2.27 * 10^-5 = X^2 / .050M

Solve and you get 2.97 .

By 9331 (9331) on Tuesday, May 13, 2003 - 03:28 pm: Edit

It was acid rain though, wasn't it?
I wrote the equation
CaCO3 + H2SO4--> H2CO3 + CaSO4
then went on to the next question. would i get any credit for that?

By Chronofx (Chronofx) on Tuesday, May 13, 2003 - 03:31 pm: Edit

dont know, i think there were 4 parts and i believe it was a question from 0-8, so you probably get 1 point for the explanation if you had one and one point for the equation.

just a guess though.

By Baseballtwin86 (Baseballtwin86) on Tuesday, May 13, 2003 - 03:34 pm: Edit

Equation is wrong though

H2CO3 breaks up into Water and CO2

By Juice (Juice) on Tuesday, May 13, 2003 - 03:37 pm: Edit

H2CO3 breaks into H20 and C02... That 2.97 sounds right for eq point.

======
Precision was good.. accuracy is not enough info
MM = 120 sounds correct.. altho im not sure what the q was.
=====

By Absurdistx (Absurdistx) on Tuesday, May 13, 2003 - 03:42 pm: Edit

I got 125... .5 g /.004 moles = 125 molar mass

By Sosodef (Sosodef) on Tuesday, May 13, 2003 - 04:08 pm: Edit

I TOLD YOU GUYS YESTERDAY THAT MY TEACHER SAID IT WAS GOING TO BE A KB PROBLEM NOT GAS BUT PEOPLE DECIDED TO IGNORE ME......FINE WELL I KNEW IT

By Mew246 (Mew246) on Tuesday, May 13, 2003 - 04:12 pm: Edit

i thought the rate open response was really easy. Wat was the answer to the last part of it asking the electrons? Also, people who are taking the makeup chem ap test, dont they have an advantage of knowing wat their open response is? I know ets isnt dumb, but im not so sure...

By Eurostar (Eurostar) on Tuesday, May 13, 2003 - 04:44 pm: Edit

I dunno what that last one was...did someone do the first reaction for FRQ 4? What did you get? Wasn't it a precipitate reaction?

By Eurostar (Eurostar) on Tuesday, May 13, 2003 - 04:45 pm: Edit

Also..what about FRQ 1..what did everyone get for Kb? I really really think i screwed that up...also, if I get a wrong pH, but use the correct indicator for that pH and explain my reasoning, do they still give me the point for the indicator part?

By Madrigal (Madrigal) on Tuesday, May 13, 2003 - 05:06 pm: Edit

I did the first Rxn. I'm pretty sure it was a precipitate--I can't remember what the precipitate was though. I thought the 1st FRQ was tough although I tend to over-complicate things. The multiple choice wasn't as bad as some of the other year's MC that I had practiced.

By Darkfyre (Darkfyre) on Tuesday, May 13, 2003 - 05:15 pm: Edit

doesn't ets make a special test just for them?

By Ndhawk (Ndhawk) on Tuesday, May 13, 2003 - 05:17 pm: Edit

my teacher had predicted kinetics and acid/base equilibrium, whatd you guys get for c in the first required free response? I got all of d right, 5 moles of electrons right at the end of number three? I chose 3 and 7, I suck at molec geometry so i opted out of 8, oh my god the equations were easy guaranteed 15 right there, there was a strong base/strong acid, a double displacement, and a single displacement, and a few other easy ones like magnesium + oxygen, why doesnt ammonia form even with a negative gibbs free energy, it should be spontaneous in the positive direction if it has a negative value, and it does at low temperatures, i just said that the value was small so the amount was negligible, I feel like I did well on the mc, i dont see myself getting lower than 50 points on the mc, and i had solid free responses aside from one part of the equilibrium, i nailed the other calculation, nailed the equations, nailed the entropy, did pretty well on the spectrophometer, except I thought na was yellow? i missed that one part, and the part where you had to verify a bunch of stuff, i got most of them, hopefully i got a 5

How many points do you need to get a 5? I know you should have at least 46 on the MC, but totally how many gives a 5?

By Ndhawk (Ndhawk) on Tuesday, May 13, 2003 - 05:19 pm: Edit

the first reaction was zinc carbonate with sulfuric acid you had to write it like this:
ZnCO3 + H ion + HSO4- --> ZnSO4 + CO2 + H20, h2co3 is always written as carbon dioxide and water, and sulfuric acid is diprotic and has to be written like i did.

By Ndhawk (Ndhawk) on Tuesday, May 13, 2003 - 05:25 pm: Edit

if you need 100/160 to get a 5? 75 points is mc, so would it then be 85 for fr? and I know the weightings, 20 percent for the first two, and 15 percent for the next 4, so would it be 20 percent of 85?

By Venomshockx (Venomshockx) on Tuesday, May 13, 2003 - 05:25 pm: Edit

here's bits and pieces of what i remember:
MC:
oxidation number of Tc = +2.5
partial pressure = 730
first ionization energy? = K?
weak electrolytes = partial dissociation
density = 11.0 (sig. figs)
the student working with a hydrous compound? keep heating until constant?
Which flask/equip is used for measuring a solid disp. in a liquid? (i skipped that one)
that one question with a XF3 where F3 is 50%? i got like 57g or something
Ag+ + NH3 --> Ag(NH3)4+ because of LEWIS definition?
Why cant a solid NaOH be used? because it'll have too fast and too violent of a reaction?
something about Pb + I = PbI3, i dun remember, its juss a part of a question


FRQ: (3 or 8):
how many electrons transferred?
What was the rate law? what were the orders for the Br-, BrO3-, and H+?
What was the indicator used? (erythrosin(sp?) pKa=3?)
Hvap of the propane groups? related to the IMFs?
how many sigmas and pis? was it like 6 and 2 respectively?

errr . . .ill post more when i can think of them

By Nifty101 (Nifty101) on Tuesday, May 13, 2003 - 05:28 pm: Edit

anyone know what "score withholding" is all about? do you specify that you want scores withheld (by June something) even if you didn't name any colleges?

By Ndhawk (Ndhawk) on Tuesday, May 13, 2003 - 05:28 pm: Edit

for 3, I got 5 moles of electrons, and the orders were 1,1,2, i didnt know whether i had to put out the number so i did, i did avagadro's number times 5, i didnt do 8 it was hard, and 7 was easy

By Nifty101 (Nifty101) on Tuesday, May 13, 2003 - 05:28 pm: Edit

say you get a bit more than half on the FR questions, and get a raw score of 50ish.... is that a 5?

By Venomshockx (Venomshockx) on Tuesday, May 13, 2003 - 05:29 pm: Edit

Ooo

Magnesium ribbon burned in air
Mg + O2 --> MgO? or is it MgO2? or are both acceptable?
I hate those equations, but thats worth 3 pts EACH ... (1 pt for correct reactant, 2 pts for correct product)

By Ndhawk (Ndhawk) on Tuesday, May 13, 2003 - 05:30 pm: Edit

im going to start an aim chat, the name is apchem everyone come and we'll discuss whatever about the test

By Jason817 (Jason817) on Tuesday, May 13, 2003 - 05:32 pm: Edit

HA! I TOLD YOU ALL IT WAS ON SPECTROPHOTMETERS!!!

I still bombed that part. Had no idea how to do any of them. I asked my teacher afterwards and he had no idea what Beer's Law was.

Anyways, the multiple choice was pretty hard. Ommitted 15 or so.

The free response was hard as hell. For #1, I could only get part a and b, and I chose #3 which I did pretty well on. The reactions were tough but not that hard. The lab question and everything after that was hard as hell. Don't know if I got any of them right.

How the hell do you do the lab sextion. I bombed the whole section. I was the only one in the class that knew about it too and everyone did better than me. Dammit.

By Ndhawk (Ndhawk) on Tuesday, May 13, 2003 - 05:33 pm: Edit

its mgo, mg is +2 and o is -2

By Darkfyre (Darkfyre) on Tuesday, May 13, 2003 - 05:40 pm: Edit

When you put silver in ammonia, it does NOT complex. The ammonia yields OH- ions in solution because it is a strong base. The net ionic equation, therefore, is

Ag+ + OH- --> Ag(OH)2

because all common metal hydroxides are insoluble.

By Flippanda328 (Flippanda328) on Tuesday, May 13, 2003 - 05:47 pm: Edit

I completely bombed the lab question, and I didn't get to part of d and e of question 1, and I may have lost on point on another question. I know for sure i aced everything else. So i probably lose about 12-15 points on free response

I left 9 MC blank. Of the ones i answered, i think i got around 5-10 wrong.

Do I have any chance for a 5?

By Heatwave345 (Heatwave345) on Tuesday, May 13, 2003 - 05:53 pm: Edit

ummm....NO

Silver plus EXCESS Ammonia is a complex reaction

By Flippanda328 (Flippanda328) on Tuesday, May 13, 2003 - 06:02 pm: Edit

No to me,no to Darkfyre, or no to both?

By Firedup17 (Firedup17) on Tuesday, May 13, 2003 - 06:15 pm: Edit

AAAHHH!!! I think I did bad. Out of all the people that took it, I was the only one that felt like getting a 2. For the MC's, I answered about 50, was sure on 15-25, and then guessed (educated guess!) on the rest. As for the free response, I did not even answer parts b),c) and d), but I know that I aced or partially aced the questions about the rate law and the Beer's Law.

Overall, I think I will get a 2.

By Dxiw (Dxiw) on Tuesday, May 13, 2003 - 06:19 pm: Edit

for the first free res, I got 3.3 pH and equivalence point at 2.6pH ... I know its different from you alls, but I remember double and triple checking. Anyways, I hope you guys remembered units on everything, I stuck units on every step of every free res and then crossed them to make sure it all balanced out.

By Venomshockx (Venomshockx) on Tuesday, May 13, 2003 - 06:21 pm: Edit

Can someone post up how the E0(V) was calculated (Its FR3 i think)? i got E = +2.29V by doing something similar to Hess's Law. Were we supposed to use the E0cell = E(cathode) - E(anode)? Cuz i dont think it was a galvanic cell.

By Juice (Juice) on Tuesday, May 13, 2003 - 06:22 pm: Edit

Flipp: If you get all th MC right that u answered you should get a 5.. if you missed quite a few ull get a 4

By Firedup17 (Firedup17) on Tuesday, May 13, 2003 - 06:24 pm: Edit

Venomshockx: I also got +2.29 V for the Rate Law Free Response one. I think it's right.

By Juice (Juice) on Tuesday, May 13, 2003 - 06:27 pm: Edit

used to measure.. volumetric flask :)

largest first ionazation energy = Br
the [Ar]s1 electron config ion was Ca

odorless gas = N2

By Giants (Giants) on Tuesday, May 13, 2003 - 06:49 pm: Edit

i don't think it was 2.29 because you had to subtract. i think it was something like .445V.

By Ivyhope (Ivyhope) on Tuesday, May 13, 2003 - 07:02 pm: Edit

Does anyone know where I can find score conversions (like how many I got out of 160) for an AP Chemistry Test?

By Ivyhope (Ivyhope) on Tuesday, May 13, 2003 - 07:02 pm: Edit

Giants - I got the same answer as you .445 V

By Jason817 (Jason817) on Tuesday, May 13, 2003 - 07:24 pm: Edit

"how many electrons transferred?"
5
"What was the rate law? what were the orders for the Br-, BrO3-, and H+?"
[Br-][BrO3-][H+]^2


"What was the indicator used? (erythrosin(sp?) pKa=3?) "
yeah that one.

By Darkfyre (Darkfyre) on Tuesday, May 13, 2003 - 07:26 pm: Edit

Hmm, I stand corrected:

From a lab procedure:
"While stirring, add concentrated ammonium hydroxide dropwise to the silver nitrate solution in the beaker until the gray-black silver hydroxide, AgOH, precipitate forms. Continue adding concentrated ammonium hydroxide dropwise with swirling until the silver diammine ionic complex, Ag(NH3)2+ (aq), forms and the solution JUST becomes clear and colorless. "

Either answer is correct.

By Flippanda328 (Flippanda328) on Tuesday, May 13, 2003 - 07:28 pm: Edit

wait... isn't [Ar]4s1 K? [Ar]4s2 would be Ca. Ca+ would be [Ar]4s1. I'm not sure, but I don't think any of the choices were in ionic form.

By Sixtoes (Sixtoes) on Tuesday, May 13, 2003 - 07:33 pm: Edit

OK, these are the weights for the 2002 AP, same for this year (although my point values may be off- I tried).
MC:

45%, 75 problems, -.25 for wrong answers. Each answer is worth .6% of your total grade.

FRQ:

Question 1, Equilibriium: 20% of 55% = 11% of your total grade. usually 9 points, so each point is worth 1.2% of your point total.
*this was your WEAK BASE problem.

Question 2 or 3, Calculation: 20% of 55% = 11% of your total grade. usually (8 or) 9 points, so each point is worth 1.2% of your point total.
*GAS or KINETICS problem. (mostly)

Question 4, Net Ionic Equations: 15% of 55% = 8.25% of your grade. 15 points possible, 3 for each reaction. Each point is worth .55% of your final grade.
*EQUATION WRITING.

Question 5, Lab: 15% of 55% = 8.25% of your grade. ~9 points possible, so each point is worth ~.9% of your final grade.
*SPECTROPHOTOMETER/ COMMON LAB KNOW-HOW

Question 6, Required Explanation: 15% of 55% = 8.25% of your grade. ~9 points possible, so each point is worth ~.9% of your final grade.
*EXPLAIN PHENOMENA: boiling pts, condensation, non-ideal gas, acid rain

Question 7 or 8, Explanation: 15% of 55% = 8.25% of your grade. ~8 points possible, so each point is worth ~1% of your final grade.
*THERMODYNAMICS or SOMETHING WITH O-CHEM.

This adds up to be roughly 100%. Add up the percents you think you got right, for example 65%. The AP scorers do it differently, and your score is out of 160, but I don't know how this works. So to simulate that, multiply 160 by the percent you got right. Example (160)*(.65)= 104. I've heard that the cutoff for a 5, while varying from year to year, is around 100 or 105. I'm pretty sure a 4 is ~80 points, but I'm not sure about the rest. Anyways, this should give you an idea of what your score is. Hope this helps.

By Ivyhope (Ivyhope) on Tuesday, May 13, 2003 - 07:34 pm: Edit

thanks

By Darkfyre (Darkfyre) on Tuesday, May 13, 2003 - 07:37 pm: Edit

Wow, you could basically just walk in, having never taken the class, and get a 3. That curve is mad generous, I think I got like an 8

By Sixtoes (Sixtoes) on Tuesday, May 13, 2003 - 07:38 pm: Edit

i'm not exactly sure on the 100 being a 5 thing. could anyone check their review books? i don't have one. don't wanna give false hope =)

By Rsxman (Rsxman) on Tuesday, May 13, 2003 - 07:40 pm: Edit

Electron transfer is 5e-???

how...I mean the first reaction was with 2e-, the second was with 5e-. Dont you have to balance them out to get e- transfer?

By Sixtoes (Sixtoes) on Tuesday, May 13, 2003 - 07:43 pm: Edit

yeah, you multiply the first one by -(5/2). because if you look at the equation at the top of the question- you want to get /that/ using the half reactions.

By Jason817 (Jason817) on Tuesday, May 13, 2003 - 07:50 pm: Edit

"Electron transfer is 5e-???"

I got 10 e- because I added 5 from each equation. But if you reveresed the top one and multiplied by 5/2, then you get 5e- for the top and bottom equation.

By Sixtoes (Sixtoes) on Tuesday, May 13, 2003 - 07:55 pm: Edit

no its /transfer/. like one side gives up 5 e-, the other accepts 5 e-.

By Jason817 (Jason817) on Tuesday, May 13, 2003 - 08:01 pm: Edit

Yeah I know. I was saying I got the wrong answer and was trying to explain why I was wrong.

By Sixtoes (Sixtoes) on Tuesday, May 13, 2003 - 08:01 pm: Edit

hey, someone invite me to the ap chem chatroom. sn is moxiepoxiedeux. thanks.

By Me1 (Me1) on Tuesday, May 13, 2003 - 08:06 pm: Edit

If you didn't label the units of your answers (assuming u used the same units given in the problem), will u lose points? (I know one of the rate laws problems said to label, but if u forgot on others is it ok?)

By Sixtoes (Sixtoes) on Tuesday, May 13, 2003 - 08:08 pm: Edit

depends.

By Venomshockx (Venomshockx) on Tuesday, May 13, 2003 - 08:38 pm: Edit

To anyone who did FR 8:
(a) for the propanone did your drawing look something like:
CH3-C=O ---CH3(bonded to central C) ?
(b) how did the structural isomer look? where does the third branch attach?
(c) What was the bond angles? Central C = 120°, and the other two C = 109.5?
I thought the middle carbon made a trigonal planar, while the other carbons were tetrahedral. am i right?

(d) For the drawing of the other organic molecule, what was the hybridization of the (arrow pointed to it) carbon? sp3?
(e) And how many sigma and pi bonds were there in that molecule? 6sigma, 2pi?

Am i missing any other parts to this question?

By Me1 (Me1) on Tuesday, May 13, 2003 - 08:47 pm: Edit

Can someone please invite me to the chat? SparkleDustXXX

By Chen (Chen) on Tuesday, May 13, 2003 - 08:55 pm: Edit

Wow, I definitely got the opposite on the Kb problems...So I got all those wrong. I got basic pHs.

Your teacher doesn't know Beer's Law?! That's kind of surprising.

I omitted 14 questions and guessed on a lot. I did horrible on FR and didn't explain a lot for the spectrophotometer. I hope they still give me credit.

lol, for my contribution, for the colorless question, Na is colorless.

By Rsxman (Rsxman) on Tuesday, May 13, 2003 - 09:00 pm: Edit

methane does not behave idealy at low temp and high pressure because?!

By Sixtoes (Sixtoes) on Tuesday, May 13, 2003 - 09:15 pm: Edit

because methane starts hitting itself. kinda. to invite yourself to chat, put yourself on your buddy list and invite yourself to "apchem".

By Rsxman (Rsxman) on Tuesday, May 13, 2003 - 09:19 pm: Edit

what if i put nonpolar substance.

Also, for part II where they ask why there's so little N and H in the haber process at low temp. Can I say something about Le Chatelier's Principal and say that its an exothermic Rx, and then lahblahblahblah?

By Absurdistx (Absurdistx) on Tuesday, May 13, 2003 - 09:28 pm: Edit

For the last one on #7, I just said thermo can tell you if a reaction is happening, but kinetics tells you how fast. So, for all we know, that reaction is happening, but really slowly.

By Johnnyd (Johnnyd) on Tuesday, May 13, 2003 - 09:54 pm: Edit

im pretty sure the electron transfer one was ten because you have to multiply to make sure the reactions both have the same number of electrons and the least common factor was 10

if you just put water condenses, would they give you full credit (for the ice water problem)

By New (New) on Tuesday, May 13, 2003 - 09:56 pm: Edit

props to jason817 for mentioning spectrophotometer
at least i got like partial credits instead of just leaving it blank

By Solid_Rock (Solid_Rock) on Tuesday, May 13, 2003 - 09:56 pm: Edit

For those of you who did reaction corner with the N205 + H20, i have no doubt in my mind that since
Nonmetal + Water --> Acid, the only possible reaction that could have occurred was:

N205 + H20 --> 2HNO3

even though you don't need to balance. Did anyone else get this?

By Muawan (Muawan) on Tuesday, May 13, 2003 - 10:00 pm: Edit

yes but its net ionic so its N2O5 + H2O -> H+ + NO3 -

By Absurdistx (Absurdistx) on Tuesday, May 13, 2003 - 10:13 pm: Edit

Yeah, since nitric acid is a one of the strong acids, so it dissociates 100%, right?

By Me1 (Me1) on Tuesday, May 13, 2003 - 10:15 pm: Edit

Abs, yea that's right.

Anyone get the isomer? (in #8)

By Jason817 (Jason817) on Tuesday, May 13, 2003 - 10:18 pm: Edit

you mean that long organic compound? hell no.

By Rsxman (Rsxman) on Tuesday, May 13, 2003 - 10:24 pm: Edit

how many of the Rx is ionic? cuz i didnt change it to ionic.

i mean even if its ionic, the reactant side i can still get right cuz some of them were lik

hydrogen peroxide and sunlight yields blah.

strip of magnesium or something burn it to yield blah.


jus to name a few.

By Absurdistx (Absurdistx) on Tuesday, May 13, 2003 - 10:24 pm: Edit

Haha, same here. I saw some organic crap and opted out. Plus - delta G rocked anyway (#7).

By Dxiw (Dxiw) on Tuesday, May 13, 2003 - 10:32 pm: Edit

solid_rock - thats what I put too.

By Greenmoo04 (Greenmoo04) on Tuesday, May 13, 2003 - 10:36 pm: Edit

That was the hardest test ever! At least the Essay portion wasn't as bad as I predicted. I think I might have been able to pull it off with the BS. haha. Does anyone know what the Beer equation is? It was in that spectrometer problem; we didnt even LEARN light problems so I was on my own there. Also, why does NaCl have a higher boiling pt than the sugar does? Something about molecular structure or something? Oh well, It's over FINALLY.

By Rsxman (Rsxman) on Tuesday, May 13, 2003 - 10:46 pm: Edit

can i get 50% right and still get 4?!?!?!?!?!?

By Juice (Juice) on Tuesday, May 13, 2003 - 10:55 pm: Edit

JOIN US IN aim chat room APCHEM its fun!

By Snv (Snv) on Tuesday, May 13, 2003 - 11:02 pm: Edit

i put that boiling point is a colligative property (is it? im not sure) and that in .1 M of certain volume the number of molecules is more in NaCl than the other one and that since colligative properties depend on number of molecules, nacl would produce most change


also, for 7, for the last couple parts, i said that delta g= delta h -t(delta s) and how g would become negative if h and/or s is pos/neg. is that right?

for spectrophotometer, i put 500 (i miss gauged the numbers) do you think they really care-- i explained the correct wavelength is the greatest amount of disparity between absorbtion and reflection or watever?

By Greenmoo04 (Greenmoo04) on Tuesday, May 13, 2003 - 11:14 pm: Edit

i tried to invite myself into apchem, but its not working. can someone just invite me "greenmoo04" thanks a lot!

By Greenmoo04 (Greenmoo04) on Tuesday, May 13, 2003 - 11:14 pm: Edit

i tried to invite myself into apchem, but its not working. can someone just invite me "greenmoo04" thanks a lot!

By Arashf (Arashf) on Wednesday, May 14, 2003 - 12:59 am: Edit

what did you all get for the fingerprint on spectrometer?

By Jason817 (Jason817) on Wednesday, May 14, 2003 - 01:27 am: Edit

I had no idea on that one. I said it would increase the molarity.

By Venomshockx (Venomshockx) on Wednesday, May 14, 2003 - 01:33 am: Edit

fingerprint on spectrophotometer? wouldnt a smudge on the cuvette absorb some of the light? therefore affecting the absorbance and transmittance of the readings.

thats what i put down. anyone wanna verify this?

By T0fu (T0fu) on Wednesday, May 14, 2003 - 01:48 am: Edit

I did, too, though I never studied that stuff. Said it would appear that the solution absorbed more than it actually did, and noted the effect on the graph (forgot what it was.)

By Sixtoes (Sixtoes) on Wednesday, May 14, 2003 - 02:14 am: Edit

the soln would absorb less than it would without the fingerprints. because theres a finite amount of light and the fingerprints absorb some of the light.

By T0fu (T0fu) on Wednesday, May 14, 2003 - 02:22 am: Edit

then we agree...

By Ndhawk (Ndhawk) on Wednesday, May 14, 2003 - 07:42 am: Edit

so then wouldnt the calculated absorbance and conc be underesstimated and not overestimated?

By Johnnyd (Johnnyd) on Wednesday, May 14, 2003 - 09:26 am: Edit

Hey, for the ice water problem, could i just put that water condenses and get credit?

By New (New) on Wednesday, May 14, 2003 - 11:10 am: Edit

why would it be underestimated?
i'm not sure, but i put down because the fingerprint absorbed some light of its own, then the overall absorbance is higher (not only do you have the ions in the solution absorbing the light, now you have the fingerprints doing it too)
what did you guys put?

By Jason817 (Jason817) on Wednesday, May 14, 2003 - 12:39 pm: Edit

New: I put basically the same thing as you.

By Cutlasssupremer (Cutlasssupremer) on Wednesday, May 14, 2003 - 06:06 pm: Edit

Hey everyone,
I'm so confused! What is spectrophotometry? I knew everything on the MC, and all the FRs except spectrowhateverthehell it was. We definitely never did that in my class. I checked the Barrons Review, and it's not in there either.
So I was able to answer part A of that question... how to dilute a solution. For the question about Beer's Law (??) i just put Molarity... maybe I'll get partial credit? I said that a fingerprint would absorb light so the solution would appear to be more concentrated... And then I said that cobalt is colored and sodium isnt. Totally BSed the whole thing. Could I still get a 5?


And just to respond to the ice water thing, I did heat transfers (ice to beaker to air), condensation (phase diagram), and hydrogen bonding/vanderwaals forces to explain why droplets form.

Anyway, its over. breathe.

By Humburdy (Humburdy) on Wednesday, May 14, 2003 - 08:13 pm: Edit

"Anyone get the isomer? (in #8) "

since it was a ketone (propanone), an isomer would be propanal, which is an aldehyde.

organic chem was easy...but i think i did REALLY bad on the rest. like my equivalence point was 5.3?! with some luck i can (maybe?) get a 5. is it bad to get a 4?

and how much do ap exams show your knowledge? i panicked on the exam so i couldn't think for a while. but i normally know the stuff and more, after participating in the chem olympiad.

this is so sad.

By Jason817 (Jason817) on Wednesday, May 14, 2003 - 09:14 pm: Edit

"I'm so confused! What is spectrophotometry? I knew everything on the MC, and all the FRs except spectrowhateverthehell it was. We definitely never did that in my class. I checked the Barrons Review, and it's not in there either."

It isn't in any book except Cliffs AP Chemistry. That book has 100 pages with descriptions of all 22 AP Chem labs.

By Muawan (Muawan) on Wednesday, May 14, 2003 - 09:43 pm: Edit

Spectrophotometry is using light to measure the concentration of something in a solution. The spectrophotommeter is standardized using known concentrations through Beer's law.

By Keyboardgunk (Keyboardgunk) on Wednesday, May 14, 2003 - 10:33 pm: Edit

Which element had the largest first ionization energy? I thought it was Ca..but ppl are saying it is Br.

By Nifty101 (Nifty101) on Wednesday, May 14, 2003 - 10:58 pm: Edit

anyone know what it takes to get a 5 ... say you have a 50ish raw score on the m-c, what percent of the FR must you get right?

thanks

By Eurostar (Eurostar) on Wednesday, May 14, 2003 - 10:59 pm: Edit

Br

By Sixtoes (Sixtoes) on Wednesday, May 14, 2003 - 11:07 pm: Edit

Nifty101- look at my thread "CALCULATE YOUR AP CHEM SCORE HERE"

By Absurdistx (Absurdistx) on Thursday, May 15, 2003 - 12:30 pm: Edit

About the whole first ionization energy thing... Well, I thought it could be Br first, too. But then I realized that all don't follow the trends. Br's electron configuration is [Ar].3d10.4s2.4p5 and Se is [Ar].3d10.4s2.4p4. So Br has one extra electron and Se has a pair. Wouldn't Se be more reluctant to give up an electron compared to Br? I don't know, if anyone wants to tell me why I'm wrong, I'd be glad to listen.

By Madrigal (Madrigal) on Thursday, May 15, 2003 - 03:13 pm: Edit

Absurdistx--

An electron can be removed more easily from Se beacuase when the electron is removed the 4p orbital is half full. An element is more stable with a half full orbital than a pair of electrons with 2 unpaired electrons. At least that's waht I think.

By Venomshockx (Venomshockx) on Thursday, May 15, 2003 - 08:45 pm: Edit

HEY EVERYBODY!

The 2003 AP Free Response can be downloaded here:
http://apcentral.collegeboard.com/repository/ap03_frq_chemistry_23111.pdf

Post up the solutions for them if you feel confident (and please be detailed when explaining!)

By Ivyhope (Ivyhope) on Thursday, May 15, 2003 - 10:15 pm: Edit

are the answers up anywhere?


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