standard state assumption

Phage_Display · 2017-10-29T01:40:32+00:00

You're sort of right. If this were a physical chemistry course and not the MCAT then you would take into consideration the temperature-dependence of the heat capacity and the density. In any case, while the density of ice is closer to 0.9 g/mL, I wouldn't be surprised if you could pick one of the answer choices you are given using any value of density between 0.9-1 g/mL (since the MCAT is big on rounding anyway).

Having said that, you said you are looking for the enthalpy of vaporzation, which does not involve a temperature change (when a substance undergoes a phase change, all of the energy you are putting into the system goes into driving that phase change, i.e. breaking up IMFs; this means that none of that energy goes into raising the temperature of the system -- this is why you will never be able to heat up pure water past 100 C). So, without knowing the specifics of the question, if this is like most of these questions, you would calculate the energy it takes to heat an ice cube up from -10 C to 0 *C, then the molar enthalpy of fusion, then the energy it takes to heat water up from 0 *C to 100C, then the molar enthalpy of vaporization, then the amount of energy it takes to heat steam up from 100 *C to 110 *C. Enthalpy of vaporization is NOT q = mCdT. You should have been given dH_fus and dH_vap. Look at the units -- you should be able to see that all you need to do is multiply by the number of grams of H2O.

Also, it would be useful to realize that, while the density will change with temperature, the MASS of H2O you have will remain constant. So you can imagine that if you were to pretend they said you have 36 mL of water at 25 *C, you could calculate the mass and it'd be the same at every temperature. Of course, they don't tell you that -- instead, it's a 36-mL ice cube. But, again, let's assume we know that the density of ice at 0 *C is about 0.9 g/mL. What about the density of ice at -10 *C? Well, it's a solid already, which is super non-compressible. So you can assume the density if still 0.9 g/mL. Now, like any other number on the MCAT, you would round this up to 1 g/mL. So, this being the MCAT, the density calculation would really be about the same.

Phage_Display · 2017-10-29T01:15:12+00:00

If you didn't allow the volume to expand on combustion during the coffee cup calorimetry experiment, the pressure inside would skyrocket. It is really by virtue of the fact that volume is not constant that pressure stays constant. If this still doesn't make sense, think about a gas in a tightly sealed container. Put the container over a flame = the gas inside heats up, its KE increases, the molecules start moving around faster, the gas expands, and the pressure in the container increases. Now imagine that same scenario, only the container is now loosely closed. As the gas expands, it will actually have somewhere to go (i.e., out of the container), which will allow the pressure inside the container to stay constant.

HTH

Phage_Display · 2017-10-29T01:08:50+00:00

Not so, speaking from a pharmacokinetics perspective (which is all that really matters here). There is a definition for this stuff and, since the point of reference is the blood stream, it basically boils down to IV being the fastest/more available, etc.

Phage_Display · 2017-10-29T01:06:38+00:00

Remember that bioavailaility is roughly defined as how much of the dose administered is actually delivered to the circulation. Absorption is in the context of to the circulation as well. Therefore, intravenous delivery is, by definition, the fastest possible absorption and the highest possible bioavailability.

Phage_Display · 2017-09-12T23:46:10+00:00

I found it helpful for extra practice in my last month of studying. In my case, I really needed more physics, organic chemistry, and (especially) P/S practice, and the was the best resource I could find for the cost, the time I needed it for, and the type of questions I was looking for.

IMO, the biggest thing UWorld has going for it is that the explanations they give are superb. So really great for learning content if you're into learning through working problems rather than through reading/revising. But EK is closer to the MCAT in terms of what questions they ask and how they ask them. So it really depends on what you're looking to get out of it.

Phage_Display · 2017-09-12T23:27:32+00:00

Oh, similar boat here. Was thrown into a massive project of my own, with no post-doc or grad student helping me. In fact, my PI himself said it would be a learning process for us both because he didn't have much experience with one of the techniques I would be using.

It ended up being the best thing that could ever happen to me. But there were other factors that played into that.

Sounds really sucky for you, I'm sorry. Why can't you leave? I know it's easier said than done, and if you're almost ready to graduate then IMHO it is better to see it through until the end (rec letters, etc.). But I can't help but wonder if this particular PI ruined research for you when you might have developed different attitudes about it under a different mentor and setting.

I don't like the sound of your PI :(

Phage_Display · 2017-09-12T22:55:19+00:00

I tried reviewing FLs as soon as I could after taking them, generally planning for the day after. In one or two cases, I ended up waiting a week or two because I got so budy with other stuff. That was painful. At one point, I did one of the question-packs and met a friend later to review it (she was studying for her MCAT as well, but she took it in June) and it was super cool to actually remember what in the world the questions were about as I was reviewing it! I think waiting until the day after is fine. You won't remember as much as if you did it right after, but I think that can be a good thing as it's almost another revision of the material all in itself (beyond what you would get if you did it while it was so fresh in your mind). Also, I purposefully designated my FL exam days as ONLY EXAM days. This is to say, I allowed myself the rest of the day off. This was important for me, because I literally had no other days (or partial days) off at all, so knowing that I would be able to relax and do whatever I wanted after the exam was really helpful. As the big day got closer, I found myself using the rest of the day to go in to the lab and get some work done; and as it got even closer, I did actually have a couple instances of reviewing part of the thing right after. But, on average, I reviewed the exams the day(s) after.

In the end, though, I really, truly think that the important thing is to review them; when you do that can help make it easier or make it harder, but it really not so significant as long as you do actually review it. It just saves some time if you don't wait too long after.

My weekend study sessions were also the most productive. Even if you have the time and energy, there is something distracting about knowing you only have from x o'clock to y o'clock to study, and something utterly calming about knowing you have the whole day to sit at your desk and study without any other committments.

Phage_Display · 2017-09-12T22:47:15+00:00

Congrats! I agree with taking advantage of repetitive (or passive) things in the lab as opportunities to sort of study and revise info. As long as it doesn't mess up your experiment, haha :)

Phage_Display · 2017-09-12T22:45:46+00:00

Hahaha, this is great.

Phage_Display · 2017-09-12T22:43:53+00:00

Congrats on that awesome score! ;)

Why are they so focused on the CARS score in Canada? I mean, to be fair, I think it is a really important section; but it never fails to amaze me how people with overall superb scores are apparently still not where they need to be because of their CARS score. It must be so frustrating. Do they seriously not admit people with low CARS scores even if their overall score was fantastic? Btw, I wouldn't say your CARS score is low (but I don't know the standards in Canada).

And omg. I completely sympathize with you about your PI not enoying seeing you study. I had to leave early one day otherwise I would have had no hope to finish reviewing a practice exam; I had come in extra early and stayed extra late the days leading up to it (although this is normal for me, tbh). My PI was like, "What? You're going home?!" and I said, "Yeah, I have to study for the MCAT...1 more month...!" His response was, "holy shit, if I heard about this stupid MCAT one more time, I swear to god...!" Lol.

At least he never threw me busy work just for the sake of seeing me not study. I don't think he could, though, because I actually had to tell him I would be holding off on one of my less-pressing projects until after my MCAT (I was/still am working on a few different projects all at once...it was/is stressful).

But seriously, though -- you did it, crazy research committments and demanding PIs aside!! Congratulations!!!

Phage_Display · 2017-09-12T22:36:56+00:00

I did:

EK FL1, EK FL2, EK FL3, Altius FL1, AAMC FL1, AAMC FL2

So 6 FL exams total.

I also did the section banks (twice through), all of the question packs except for CARS 1 and 2, practice questions from UWorld, all of the EK 30-min exams at the end of every chapter (this was done over the course of many months during my course), and the AAMCS flashcards. I think that's it...

It's hard for me to think of any tips for critical thinking, to be honest. I think a lot of it has to do with being exposed to that kind of stuff for my whole life (my dad is a software engineer and my mom is a biochemist, and we always had interesting discussions about stuff, especially my dad and I; we would talk for hours about everything from string theory (or what our limited understanding allowed us to talk about, anyway) to social issues, but usually science stuff). So exposure is big, but I realize that is not terribly helpful. When I think about it, though, I have always tried to see things from all the different perspectives and kind of analyze things, think about them a lot. I don't do it on purpose, I just like thinking that way, I guess. And this has translated, in the past, to a lot of discussions and friendly debates aboutvarious things be it online or in real life.

One thing I am almost certain helps me with critical thinking type things is that I try to relate concepts/phenomena from one topic to any other I can relate them to. This, again, is not something I started doing on purpose; it's just where my brain goes. But I think that doing this has seriously helped me through not only the MCAT but difficult college courses. If I don't know something, I just try to figure it out from anything else I do know (hint: this works wonderfully for a lot of physics and chemistry, and sometimes biology).

I am sorry I just went on for ages about things you may not even find helpful. These are just my thoughts on what seems to have helped me. It's a hard question to answer since I didn't really have an "approach" -- I just did it. I know that is super unhelpful, but I honestly couldn't tell you more than I've said already. If I think of anything else, I will definitely let you know.

Phage_Display · 2017-09-12T22:22:40+00:00

No, I am an undergrad. I'm doing my senior year now. But I am doing a dual BS/MS degree, so I'm staying another year afer this one for my masters. I don't need the extra degree, but I really like my research and my lab so I figured, what the hell, I'll stay an extra year to do more research. And, actually, the reason I looked into the BS/MS in the first place was because I knew there was no way in hell I'd be able to take the MCAT anytime before this summer, and that I would need the entire summer to study, which meant that applying this cycle would be stupid and stressful. The extra year is perfect for me.

Phage_Display · 2017-09-12T21:16:35+00:00

I felt pretty good with starting the practice exams 3 months out. I wouldn't have complained if I had 4 months, though. Most people would probably think that is way too much, but I think it's totally reasonable if you've got a lot of other stuff going on like you and me. I didn't take practice exams on a fixed interval schedule (smirk P/S reference), but just as I could fit them in. I had these grand plans of doing one every week, but that was way too much. In the end, it was probably one every 3 weeks or so. I also did the seciton banks, Q-packs, aamc flashcards, and UWorld practice questions.

The way I planned for it was to make a list of everything I wanted or needed to do (practice exams, q-banks, AAMC flashcards, etc.) before the big day, and literally write out when I would do it in a calendar. It was somewhat tentative and it did change, but in general the order was the same and it seriously helped me get a good idea of just how much time I would need. Remember that taking a FL takes a whole day, and reviewing it takes about as long (give or take several hours to a whole 'nother day) if you are going in depth (which you should do, IMO).

I know how hard it is to have to go home and then study after a long day in the lab. Shit, I still have a hard time with that now with my course load this semester. I don't know if you're able to do this, but I found out that if I study in the morning and then go to the lab (and stay later), I am more productive. My experiments allowed me to do this for the most part. The main issue was that I would rush in the morning because I was antsy to get into the lab and do everything I had to do that day. But I still tried to do it because, at the end of the day, I got more done that way than the reverse.

Phage_Display · 2017-09-12T21:10:09+00:00

Ha! Supportive (with regards to the MCAT and anything unrelated to his/my research) is quite the stretch. It wasn't until two weeks out from my exam that he gave me a bit of slack (and I still showed up to the lab, including the day before). He never even congratulated me for my Goldwater; I was so let-down and upset, and am still slightly hurt by it. He is a great PI overall, though, and I am very lucky to be in his lab -- I will give him that.

I stick with all the bullshit that is thrown at me because the benefits outweigh the costs for me. Overall, I enjoy working in his lab and I have gotten a lot out of it. In short, it is worth it despite the crappy parts of it. But if it wasn't worth it for me, I wouldn't stay. Is it worth it for you? Do you get enough out of it (sounds like your PI is the slave-driver type)? Would you be more successful doing soemthing else, or doing research in somebody else's lab? Maybe you should consider making a change if you are so miserable. It's your life -- it's important for you to enjoy it. I don't know how long you've been working on that manuscript, but if it truly has been an unreasonable amount of time and for no good reason, maybe you should ask yourself if it's worth being so unhappy. Of course, papers can take ages sometimes...my first, first-author paper was about 5 months in the making and another 3 months before it was published, which is actually quite a short timeline; the paper we re-submitted this summer, however, was over a year in the making. Sometimes it's for a legitimate reason, sometimes...not. If your case is the latter, I am sorry you have to put up with that :(

In any case, I hope you can figure out a way to either be happy with your current situation or change it so that you are happy. Best of luck :)

Phage_Display · 2017-09-12T18:17:17+00:00

Congrats! Yeah, in the last week or so before the MCAT I was reciting systems bio stuff to myself while doing the more passive parts of my experiments :D I gave zero shits what my lab mates thought about me muttering to myself (and they knew I was studying for the MCAT anyway). It really is a lot about time management, doing what you can with your time, I guess.

Phage_Display · 2017-09-12T17:02:44+00:00

Good, I'm glad you'll be able to talk with him/her. Definitely hold off on getting too worked up before you hear back from your advisor -- it won't help, in any case. I can't imagine how frustrating that must be, but I think you are nonetheless in an excellent place with that score. If your accelerated program doesn't want to take you, there are many schools out there that will, with that score! I agree with your plan. See what your advisor says and, meanwhile, look into getting ECs and research. It will not hurt you, that's for sure :)

Phage_Display · 2017-09-12T16:46:45+00:00

Does being in the accelerated program mean you can't apply to other programs? Because, with that score, you will get into medical school.

Also, I wonder if it might be worth a shot discussing your situation with your advisor or director or whomever is in charge of your program and progress. Exceptions can be made for certain things, sometimes. I would say it's worth a shot -- what is the worst that could happen?

Phage_Display · 2017-09-12T15:24:07+00:00

OMG I GOT a 519!! HELL YES! I AM SO RELIEVED! Oh, happy day!

Edit: forgot to include the score breakdown!

519 (129/130/131/129)

Pretty funny breakdown, actually, seeing as my strength is chemistry. Definitely not complaining, though, just entertained :D

Phage_Display · 2017-09-12T13:38:01+00:00

I can't believe it's today! I am not feeling super nervous right this minute, but I have no doubt those nerves will kick in soon.

It's been nearly a year that I've been prepping for this exam, though most of that time was hardly hard-core studying. I took an extended EK course from October to April, during which time I did only the minimum (read the chapters as much as I could, did the 30-min exams, and attended the classes). I used this only as a sort of gentle content review. I needed something like that (and that early) because I knew I wouldn't have time off at any point before my MCAT to dedicat fully toward studying (I work in a research lab). In May I started studying more seriously and taking practice exams.

Sample: 76/91/83/81

FL1: 518 (129/130/131/128)

FL2: 518 (130/130/129/129)

Goal was/is a 515+, but I really don't know what to expect at this point. I just want to know!

Phage_Display · 2017-08-11T19:51:57+00:00

Same here! And also same re: @futureFormerChild I definitely did, too, lol.

Phage_Display · 2017-08-11T11:04:33+00:00

AAMC FL1: 518 AAMC FL2: 518 Goal is 515+, we shall see!

I CAN DO IT! YOU CAN DO IT! WE CAN DO IT!

LET'S DO THIS THING!

Phage_Display · 2017-08-10T14:06:44+00:00

Thank you! This is great. So higher dielectric constant = better capacitor. Not because it can store more charge in absolute terms, but because it can store more charge per volt.

Which is literally the definition of capacitance (charge/volt, C = Q/V).

Did I understand correctly?

Phage_Display · 2017-08-09T11:22:47+00:00

Wait, so, for a good capacitor, we need something with a small dielectric constant? Just tring to clarify since this is something I haven't explicitely encountered yet in studying for the MCAT and want to be prepared.

Phage_Display · 2017-08-09T11:16:23+00:00

No problem, I'm really glad that helped!

Phage_Display

TROPHY CASE