The AP Chemistry Study Thread

[Oboesmrtguy40]

key: all FOUR....in only ONE of the four...u could square 4 into 16 and only one would be 1/16, but i could be done another way too

[Evilbooyaa]

jeez this thread took off.
nice questions guys..... but try and actually answer a question before you post one..... there seems to be MANY questions flying around right now.

if no one objects, if we can remove all previously posted questions (w/out answers) other than oboesmrtguy40's latest in post #54 and QuizQuick's in post #53. QuizQuick, I saw you had many other questions, please post them again one at a time to reduce confusion.

alright, now to answering some of these. QuizQuick- your question

b)particle size is the one that is left after Process of Elimination.
temperature affects, along w/ concentration, catalyst, and removing some of the products (chartiers principle)

smrtguy40- not exactly sure, but I think its E.
my reasoning follows

Pb+2 + 2Cl- --> PbCl2

3 moles of reactant. 1 mole of product.
reaction is spontaneous, therefore statement E is false.

[stanfordream]

hm... i think particle size will affect the reaction rate - the more surface area, the more collisions (collision theory) that will result in reaction. frankly, i think all the choices can affect reaction rate. do you have the "official" answer?

[Oboesmrtguy40]

B The entropy of the universe is increasing...thats the answer...it said which is true, not false. but u would have been right

[Evilbooyaa]

bah. i need to learn to read.
my bad.

i think i'm still right on quiz quick's though.....

Nope, it's definitely not particle size. I'm taking a computerized take home test and I got that question wrong.

[Evilbooyaa]

maybe its b? maybe the question is asking for the rate..... like kinetics. cause then, if its 1st order, the concentration doesn't matter...... idk.

[mrniceguy]

Four of the following factors can affect the forward rate of a chemical reaction.
Which one cannot affect this rate?
1) temperature
2) particle size of solid reactants
3) concentration of reactants
4) presence of a catalyst
5) removal of some of the products

Maybe the answer is 5?

[Evilbooyaa]

..... i guess the rate.... maybe. but le chattiers says that if you remove products the reaction shifts to the right.........
it seems like all of them affect.... idk. i'm way confused on this question.

[mrniceguy]

Possibly, the reaction is not in equilibrium?

Now that I read it again, I think it’s 5. The question says “forward” rate, so why should how much products you have matter if it’s not in equilibrium?

[tryingmybest]

I am reading my AP book about rate and it says that ONLY the species of a reaction AND temperature can affect the rate.

Is the question maybe flawed? I'm not sure.

I suck at equilibrium and I have a question:
If you have a reaction like A->B+C and you are given GRAMS of A, LITERS of rigid container it is put in. It is heated it says at ___ K and it lastly gives the MOLES of C at equilibrium.

Then it asks for the equilibrium concentration of gas A and gas B (all 3 are gases btw)...is this what you would do?...i think im wrong but jw...

divide moles of C by liters to get molarity ?...then make an ice chart where you see that x= Molarity C?. For A you can convert Grams-->Moles then divide by L for Molarity. Then you will have Initial M - x = final. And from C you will have x.

If you know how to do it, ignore these last 2 paragraphs and just post lol because i think i am wrong...or maybe I'm right.

[stanfordream]

i think its more complex than that due to the heating since temp changes equilibrium constant. don't know how to do it though

[sristi]

Four of the following factors can affect the forward rate of a chemical reaction.
Which one cannot affect this rate?
1) temperature
2) particle size of solid reactants
3) concentration of reactants
4) presence of a catalyst
5) removal of some of the products

OK, I did this question through the process of elimination.
A) temperature~ if you increase the temperature in an exothermic process the reaction will turn left. vice versas for an endothermic system. Thereforem it affects equilibrium.
B) I will get to this later
C) Concentration of reactants~ It matters a whole lot. eg.
X+Y--> XY
lets say you have 100 atm of XY and O atm of X and 300 atm of Y. This system will go toward the reactants to try to produce some X.
D) presence of a catalyst-- it affects the rate of a reaction as we all know by lowering the activation energy of the system.
E) Removal of some products. eg.
XY+Z-->XZ+Y
Lets say you take away some Y from the products. The system will shift left to produce some Y again.

So my answer in B). I am quite sure but if I am wrong please correct me. I want to learn

My question (sample AP)

Match the following with the statements given below. An answer can be used more than once or not at all

A) H2
B) He
C) O2
D) N2
E) CO2

(the 2s are subscripts)

1. This is the most plentiful gas in the earth atmosphere. (Kudos to those who can say what percent of the atmosphere it makes up)

2. A 1 mole sample of this gas occupying 1 liter will have the greatest density

3. At a given temperature, this gas will have the greatest effusion.

4. The molecules of this gas contain plar bonds

5. The molecules of this gas contains triple bonds.

Good Luck!

[tryingmybest]

1. N2...80%
2. CO2...NOT SURE
3. He
4. O2...NOT SURE
5. N2

2 and 4 not sure about. please correct me.
My question is posted few posts above.

Sorry if an incomplete message was posted 2ice by me. I pressed reply accidentaly and not sure if I pressed stop quick enough.