tbr acids bases

[jon stewart]

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its been years since i knew my logs well enough to be comfortable with them...for those who have done TBR acids and bases chapter and questions..do we need to know how to perform logs at this level? EK just does the whole estimation thing....

anyone have some good sites that can somewhat reteach logs....so lost...

 

[mightymoose02]

its been years since i knew my logs well enough to be comfortable with them...for those who have done TBR acids and bases chapter and questions..do we need to know how to perform logs at this level? EK just does the whole estimation thing....

anyone have some good sites that can somewhat reteach logs....so lost...

Some of the math-heavy MCATs may ask you to do some logs at the level TBR is teaching you.

I don't think it's that difficult to re-learn some of the log tricks they give you. If you do their practice problems, I think that's sufficient. If you get them wrong, just understand why. It's usually just a simple trick and a few memorization of numbers like log 2 and log 3.

More than likely, MCAT won't bombard you with logs but you never know since there's so many versions of the MCAT. Also, acids and bases are one of the easier chapters in the TBR books and most people score very high on TBR practice problems after reading thru the chapter.

 

[vin5cent0]

estimation will get you as far as you need to

 

[mightymoose02]

One interesting thing from that table is that MCAT scores and GPA has steadily been going up since 1992...basically indicates that medical school is getting more competitive (or the MCAT got easier or schools are not grading as hard - which seems less likely). I think it's been an interesting trend - I would have thought less people would have gone into medicine around the mid 90's with the internet boom. Managed care has been hard on doctors and smart college students should have figured they could make easy money going to business school. With the market crash, I think the last few years has been very difficult on most job markets - doctors almost always will be able to find work, it's just not as enjoyable with the changes in health care reimbursement, compared to things 20 years ago at least. These last comments are obviously my opinions and just some editorializing on my part - sorry for getting side-tracked

This had nothing to do with the thread. LOL... wow.

And what you just described... is only partially correct.

You forgot the ASIAN FACTOR! (Actually, this probably has more to do with the scores increasing than anything else)

 

[PinknGreenMD]

Just go to youtube and search for "quick ways to remember logarithms" there are several good teachers that show you step by step ways to solve them quickly and how to estimate based on your numbers

 

[SaharanPrince]

Hello Guys,

I have studying acids and bases using the Kaplan and the EK books, however after doing 1001 EK chemistry questions I am getting a lot of them wrong. Especially when comparing which ones are more acidic/basic and the reasons why?.etc..in addition I am getting a little confused when it comes to solving problems where you have to calculate PH of an acidic solution that has a certain ion concentration and then the answer makes no sense! PLEASE HELP! Many thanks!

 

[411309]

To be honest I think the chance of you getting a math heavy acid/base problem is like 1/100000. But I guess theres always that one chance right? The first mcat I took (yes im retake, i was ignorant/arrogant the first time and thought I could take it without doing any form of studying..and without even having physics or organic chem) was 60% physics 40% gen chem. There was nothing math heavy at all about the gen chem..there was a question on periodic table trends, and concetration and stuff. It was all kind of basic compared to the physics which was much harder. I think it's prob fine if you have a good and general understanding of the concept, but it prob wouldn't hurt to go deeper into the calculations i suppose.

 

[Suz]

math heavyQUOTE]

Logs are sooooo easy. PM me for more details. Here's the summary:

[H+] = 4.78x10^-12 Molar

to get the pH, do this:

pH = -log(4.78x10^-12)
pH = -log(4.78) + -log(10^-12)
pH = -log(4.78) - log(10^-12)
pH = -log(4.78) - (-12)
pH = -log(4.78) + 12
pH = 12 + -log(4.78)
pH = 12 - log(4.78)
pH = 12 - ~0.5
pH ~ 11.5

The MCAT will give you things like
(A)10.2
(B)11.6
(C)12.9
(D)13.2

So you know it's (B)

 

[Samchik]

You could've solved this question much faster if you notice that pH must be between 11.0 and 12.0 since (4.8 x 10^-12) is greater than (1.0 x 10^-12) => pH of 12, and less than (1.0 x 10^-11) => pH of 11.

 

[MajinVegeta]

i remember that chapter. It helped me to TA gen chem acutally, not for the mcat.

 

[Erythropoietin]

tbr has all you need. if you cant get through it, read a random log question and the math like 3-4 times and try to memorize it (I know you are not supposed to memorize math).. after you memorized it, then look at the question by covering the answers and solve the question by yourself until you get the correct answer... once you get the correct answer, change the question by yourself by inserting different numbers than the ones given (such as log9.8x10^-12 ...instead of the given log7.0x10^-11) ...i just made this up but you get the idea. then plug in at least 4-5 different numbers until you get it correct (and you check your answer with a calculator of course).
that's one way to get around with it

 

[HerbalPlz]

You could've solved this question much faster if you notice that pH must be between 11.0 and 12.0 since (4.8 x 10^-12) is greater than (1.0 x 10^-12) => pH of 12, and less than (1.0 x 10^-11) => pH of 11.

This is the method I use and it saves me so much time. Almost no calculations involved and takes me MAX 10-15s. Also a lot less careless mistakes because of negative signs and what not.

TBR teaches this and it really is the best imo...learn the range where your answer must lie, no need to be so precise to find out the exact answer.

 

[Samchik]

This is the method I use and it saves me so much time. Almost no calculations involved and takes me MAX 10-15s. Also a lot less careless mistakes because of negative signs and what not.

TBR teaches this and it really is the best imo...learn the range where your answer must lie, no need to be so precise to find out the exact answer.

👍 Agree! Also, I like how TBR manipulates logs with log2. However, like you said, we usually just need to approximate the correct answer.