The Official June 2015 MCAT Thread

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dickfacedan said:
If you knew close to the power that the constants were to you didn't need to do any math really because the answers were so spread out.
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True, but you also have to know the conversion factor (or power) of eV, which I didn't think was very fair. And that was my problem, I couldn't relate eV and Joules
 
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Sir.SavaLottaLife said:
True, but you also have to know the conversion factor (or power) of eV, which I didn't think was very fair. And that was my problem, I couldn't relate eV and Joules
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Fair enough. I agree with you guys though...I just don't understand the point of questions where constants and conversion factors aren't given and they are in unfamiliar units
 
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soccergurl1987 said:
Exam 1 (May 17) - 77%
Exam 2 (June 5) - 83%
Exam 3 (June 12) - 78% (I was half asleep for the physical sciences section and did by far the worse I've ever done, so it dragged my score down a little...lets hope I'm a little more awake on test day 😛)

I took the AAMC full length between Exams 1 and 2.
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damn, that's impressive. Good job! By your username I can see we're about the same age, haha. It definitely sucked having to learn all this **** from scratch 6 years later.
 
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I agree drrao! While working full time nonetheless. That said, i feel like it all has come together better now, and makes more sense holistically, than the first time i learned it.
 
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Can someone remind me in what situation the coefficient IS included in the equilibrium expression itself'; in addition to the exponent (choice C) ?!

I know that in some situation you have to consider it TWICE (as the exponent and the coefficient), but its not coming to me!
 

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drrao88 said:
damn, that's impressive. Good job! By your username I can see we're about the same age, haha. It definitely sucked having to learn all this **** from scratch 6 years later.
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Haha, thanks! Agreed. Relearning is the worst. I'm 9 years removed from all my first year classes, so it's been quite a process. I'm so nervous, but I just can't wait to be finished. I finish up TAing at about the same time (and I get July-August off of teaching...YAY!), so I'll be back to doing just lab work and my normal out of school/work stuff and I can't wait!

Fingers crossed that we all do really well so we don't need to take this test again.
 
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soccergurl1987 said:
Haha, thanks! Agreed. Relearning is the worst. I'm 9 years removed from all my first year classes, so it's been quite a process. I'm so nervous, but I just can't wait to be finished. I finish up TAing at about the same time (and I get July-August off of teaching...YAY!), so I'll be back to doing just lab work and my normal out of school/work stuff and I can't wait!

Fingers crossed that we all do really well so we don't need to take this test again.
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...oh crap. i just count the years from graduation to make myself feel less old :X but yea, I am 9 years out also. haha
 
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drrao88 said:
Can someone remind me in what situation the coefficient IS included in the equilibrium expression itself'; in addition to the exponent (choice C) ?!

I know that in some situation you have to consider it TWICE (as the exponent and the coefficient), but its not coming to me!
Click to expand...

I'm not actually sure. I thought that typically you only included those coefficients if you were writing it in terms of a variable like X. So in this case: Ksp=4x^3 (from Ksp =[x][2x]^2). If I were answering that question I would have picked D. Maybe someone else can clarify?
 
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drrao88 said:
Can someone remind me in what situation the coefficient IS included in the equilibrium expression itself'; in addition to the exponent (choice C) ?!

I know that in some situation you have to consider it TWICE (as the exponent and the coefficient), but its not coming to me!
Click to expand...

i believe it is any time you are calculating an equilibrium constant? I was looking that up myself today...
 
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i know for sure it's equilibrium constant, dissociation constant, and solubility product constant...those are all K values, so i'm thinking it is for any K?
 
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To what extent are you fellas memorizing Glycolysis and Krebs cycle. It seems like quite a time waster...
 
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soccergurl1987 said:
I'm not actually sure. I thought that typically you only included those coefficients if you were writing it in terms of a variable like X. So in this case: Ksp=4x^3 (from Ksp =[x][2x]^2). If I were answering that question I would have picked D. Maybe someone else can clarify?
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So the Ksp of: Ksp =[x][2x]^2) in variables would be accurate for a compound like MgCl2? Yet if its not in variables it's equal to Ksp =[Mg][Cl]^2)???
 
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drrao88 said:
Can someone remind me in what situation the coefficient IS included in the equilibrium expression itself'; in addition to the exponent (choice C) ?!

I know that in some situation you have to consider it TWICE (as the exponent and the coefficient), but its not coming to me!
Click to expand...

I got this wrong too!

So from what I figured out the actual Ksp expression does not use coefficients when you're only describing the formula for the solubility equilibrium, similar to Keq. But if you're using that formula to solve a problem with the compound dissolving, coefficients come into play.

http://www.coursesaver.com/showthre...used-differently-for-expressing-Ksp-s-and-Keq
 
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the only point of transforming Ksp=MgCl2 into Ksp=X*2x is so that you only have one variable, X, instead of two. So if Mg=X and Cl=2x, then plug it into your Ksp equation, Mg*Cl^2 and you get X*2x^2.

I think it's just easier to think of it as always being in the X variable format for all K equations.
 
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timsk said:
Number 9 asks what variables are needed to know the current associated with NVC pulse? Are you talking about that one?
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timsk said:
i have no idea on that one tbh...i stared at it for quite a while. I sort of thing there is a mistake because, for the life of me, i cannot see how figure 2 says anything about long term memory, or anything in the passage for that matter. I also did POE and decided between B and D. B seemed even more of a stretch than D, so i guessed D. Sorry that's not very helpful :-/
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timsk said:
I agree drrao! While working full time nonetheless. That said, i feel like it all has come together better now, and makes more sense holistically, than the first time i learned it.
Click to expand...

soccergurl1987 said:
Haha, thanks! Agreed. Relearning is the worst. I'm 9 years removed from all my first year classes, so it's been quite a process. I'm so nervous, but I just can't wait to be finished. I finish up TAing at about the same time (and I get July-August off of teaching...YAY!), so I'll be back to doing just lab work and my normal out of school/work stuff and I can't wait!

Fingers crossed that we all do really well so we don't need to take this test again.
Click to expand...

drrao88 said:
...oh crap. i just count the years from graduation to make myself feel less old :X but yea, I am 9 years out also. haha
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Oh man, now you guys are getting in my head. I am 12 years out. Hahah, my classes aren't expired right. All kiding aside there are a few schools that wont event accept undergrad classes that haven't been completed in the past 7 years.
 
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You should call them and ask because I know some of my friends who recently applied were out of school more than what the school required and they were allowed to apply after explaining their story. Doesn't hurt to try.
 
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mikil100 said:
Going over my word document of lessons learned, reviewing amino acids, and note cards. No passages, no in depth reading. Probably will take 4 hours of my time which is nothing.

Then I'm going to hopefully watch Jurassic World because dinosaurs.
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Jurassic World is a great MCAT review. All the talk about genetics and evolution. And the little kid in the movie - he knows more than most pre-meds I know. Hahahaha. He's about 6 years old and knows the purines and pyrimidines, and you hear him talking about proteins in plasma membranes. :laugh:
 
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I have a question on the AAMC FL in the CP section. It is #23.

"Suppose at the end of reaction 1 (a gas producing rxn) the level of aqueous solution was 26cm higher inside the buret than outside. Compared to ambient pressure, the pressure of gas inside the buret will be"

Answer: Lower.

Can someone explain? I may be overthinking it.
 
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pilumnus said:
I have a question on the AAMC FL in the CP section. It is #23.

"Suppose at the end of reaction 1 (a gas producing rxn) the level of aqueous solution was 26cm higher inside the buret than outside. Compared to ambient pressure, the pressure of gas inside the buret will be"

Answer: Lower.

Can someone explain? I may be overthinking it.
Click to expand...

Isn't explained by Boyle's Law? P ~ 1/V. Gas expands volume, as evident by the rise in solution level, so decrease in P.
 
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piii said:
Isn't explained by Boyle's Law? P ~ 1/V. Gas expands volume, as evident by the rise in solution level, so decrease in P.
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I guess why I am confused is because the passage says the water level in the buret started at 50cm. After the reaction it dropped to 26cm. So since volume decreased pressure should increase?
 
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the level in the buret stops moving when the pressure of everything inside the buret (the water AND the air) equals the atmospheric pressure. This is because the atmospheric pressure is pushing down on the dish of water, which then pushes it upside the buret. When the pressures are equal, there is no force to continue pushing the water level up. So therefore the pressure of only the air inside the buret has to be less than the pressure outside. The setup described is essentially how we determined that atmospheric pressure is equal to 760 mm Hg.
 
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bndf said:
For those who took the AAMC FL, I was wondering if you guys can help me out.
CP section - passage 6: When they mention affinity constant (Ka and K0), is this the same as Michaelis constant (Km)??
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Hey. This confused me too when I looked at it. I think Ko = affinity of only CPFX and Ka = affinity of CPFX at a certain site or with a metal cofactor. So the expression Ka/Ko is kind of like a "percentage" of affinity. So a Ka/Ko of .5 means that whatever it is bound with caused it to lose about 50% of its binding capacity.

Correct me if I'm wrong.
 
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also, boyles law may not be be applicable because that is when temperature is constant and in this case the temperature is likely variable?
 
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pilumnus said:
I have a question on the AAMC FL in the CP section. It is #23.

"Suppose at the end of reaction 1 (a gas producing rxn) the level of aqueous solution was 26cm higher inside the buret than outside. Compared to ambient pressure, the pressure of gas inside the buret will be"

Answer: Lower.

Can someone explain? I may be overthinking it.
Click to expand...


Simple answer:
The pressure is lower in the buret because the atmospheric pressure is pushing the water up above the water level of the container. If the pressure was higher in the buret the water level would be lower. If the buret was open the water level would equilibrate
 
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timsk said:
also, boyles law may not be be applicable because that is when temperature is constant and in this case the temperature is likely variable?
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I think the temperature is assumed to be constant. Nothing else is mentioned to think otherwise.
 
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mikil100 said:
Simple answer:
The pressure is lower in the buret because the atmospheric pressure is pushing the water up above the water level of the container. If the pressure was higher in the buret the water level would be lower. If the buret was open the water level would equilibrate
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That makes sense. However the passage states the water level starts at 50cm in the buret. So the water level is actually dropping to get to 26cm.
 
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pilumnus said:
That makes sense. However the passage states the water level starts at 50cm in the buret. So the water level is actually dropping to get to 26cm.
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Yeah it was worded weird. Didnt they have it hooked up to a vacuum? I don't remember the question specifically
 
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so since the water level is dropping from 50-26cm, the pressure in the buret should be higher to push out the water. (as volume goes down, pressure goes up, per Boyles)
 
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pilumnus said:
Yes they did in order to raise the water level to 50cm in the buret
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If I am remembering the question correctly, they reacted some gas in the buret, right? So the liquid was initially at 50cm,however it decreased to 26cm after the reaction was completed? If this is the case it is because the pressure did rise, however, the pressure of the gas from the reaction is still not greater than the pressure of the atmosphere
 
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mikil100 said:
If I am remembering the question correctly, they reacted some gas in the buret, right? So the liquid was initially at 50cm,however it decreased to 26cm after the reaction was completed? If this is the case it is because the pressure did rise, however, the pressure of the gas from the reaction is still not greater than the pressure of the atmosphere
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If it's not greater than atm, then how did it push volume out of the buret?
 
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mikil100 said:
If I am remembering the question correctly, they reacted some gas in the buret, right? So the liquid was initially at 50cm,however it decreased to 26cm after the reaction was completed? If this is the case it is because the pressure did rise, however, the pressure of the gas from the reaction is still not greater than the pressure of the atmosphere
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this is the correct line of reasoning.i also got this question wrong because I was comparing internal pressure before experiment to internal pressure after experiment. When in reality all of that was smoke screen for the simpler question.
 
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pilumnus said:
If it's not greater than atm, then how did it push volume out of the buret?
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Thats the reasoning I used.

I think it is because it's assumed the gas is less dense than the water, so it must rise, displacing the water. The water equilibrates to an extent, but the system still has lower pressure than the atmosphere.

If the buret had an initial pressure of 0 ( a vacuum, hence filing with water) and then a gas was reacted, increasing the pressure in the buret, but not to 101,000 Pa, the water level will decrease, but not entirely, because it is still below 101,00 Pa.

I'm not the best at PS. Does anyone else have an ideas?
 
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I know the exam Friday/Saturday is gonna be different. I'm just hoping neither group has to deal w a brutal PS section, since the consensus for May was that theirs was not difficult.
 
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drrao88 said:
I know the exam Friday/Saturday is gonna be different. I'm just hoping neither group has to deal w a brutal PS section, since the consensus for May was that theirs was not difficult.
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Yeah. This.

Does anyone know how our scores are calculated? I know April set the bench mark, but does it go question by question?

Like, if we have a really hard PS section and we all score poorly on it (raw score), then are we disadvantaged compared to those who had an easier PS section? Or is each individual question weighted in its own way?
 
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mikil100 said:
Yeah. This.

Does anyone know how our scores are calculated? I know April set the bench mark, but does it go question by question?

Like, if we have a really hard PS section and we all score poorly on it (raw score), then are we disadvantaged compared to those who had an easier PS section? Or is each individual question weighted in its own way?
Click to expand...

+1 on this!! Im also curious.
 
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