F**k Buffer Solutions

[bickelz]

Ok, so I just got out of my chem 123 test and I failed that shit. Like, hardcore in the butt. It was 8 questions, 6 multiple choice (10 pts each) and 2 short answer (20 pts each). The multiple choice ones were really easy so I think I did well with those ones. I didn't even know where to begin with the multiple choice ones. After an hour of staring at the bastards trying to figure them out, time was up.

So, here's where my rant begins.

If you are a college professor writing a test, put material on the test that was in the mothafucking chapter bitch. If you want to make an extra credit problem out of the material that is for a 300 level class in a 100 level class, be my guest. But bitch, don't 'spect me to know shit that ain't in the chapter and then make it 40% of my grade on the damn test. I mean, for real.

We covered things that have to do with lots of different buffer solutions but we didn't see anything like this. It was like fuckin' Normandy.

1. How the hell do you calculate the volumes of differing pH values of HC2H3O2 you need to add to get a specific buffer pH? pK was given as well as total volume and M of the buffer solution.

2. How the fuck we supposed to get to a target pH when adding acetic acid and NaOH. You can calculate the pH of the acetate ion at equilibrium with water after you have reached the equivalence point in the titration but Idk how the hell you get to a target pH from there. You would need to outstrip the buffer, which we didn't talk about doing in class. And, there wasn't even no damn buffer there. It was just at equilibrium with water. WTF!!!!!!!!!!!!

So yeah, I failed. That was the worst I have ever done on a test. I cannot wait for this quarter to be over. Now I get to go to my lab!

 

[Detective Conan]

Just don't let your anger guide you to mixing gasoline and styrofoam...

I know how it is to have a professor pull that sort of stunt. My psych professor does something similar, although I wouldn't call it as bad as what is sounds like your chem prof did. My psych prof tells us to ignore certain things, then puts said things on the test. He caught a lot of us off-guard with this second test, but I didn't let myself get fooled again for the most recent test. I think your situation is worse, however, since the information wasn't available to you in the scope of what you were supposed to be studying.

 

[Phage]

1. Can't you use the henderson hasselbalch equation and use it to get the molarities of the acid and conjugate base. That way you could maybe do a ratio of the volumes? I'd have to see the problem.

2. I think this is an ICE chart problem?

I've already gone through chem. I feel for you.

I suggest this for extra practice and summary explanations of concepts.

 

[Sloe Djinn]

Just don't let your anger guide you to mixing gasoline and styrofoam...

Homemade napalm ftw.

 

[bickelz]

1. Can't you use the henderson hasselbalch equation and use it to get the molarities of the acid and conjugate base. That way you could maybe do a ratio of the volumes? I'd have to see the problem.

2. I think this is an ICE chart problem?

I've already gone through chem. I feel for you.

I suggest this for extra practice and summary explanations of concepts.

@Phage The Henderson hasselbech equation is used for buffer solutions. Since you know about this I will post what I remember from the question.

A chemist wants to prepare a buffer solution with pH of 4.65 (not sure if that was it but is was around there). He starts with 471 mL of a 0.0791M solution of NaOH. How many mL of pure acetic acid will it take him to get to the target buffer pH? (pK and density were given for the acetic acid).

So I started with equivalence point titration.

Acetic acid (HA) + NaOH -> Water + Acetate ion (A-)

So, after titrating to the equivalence point, you have the conjugate base reacting with water...

A- + H2O -> HA + OH-
I
C
E

Now, you have the initial concentration of A-. Can you use the HH equation here? Would acetic acid just be the buffer? You would have to then add enough acid to outstrip the OH- ion and neutralize the solution right and then add more acetic acid? But if that's how it works, there is no more buffer, just acetic acid at equilibrium with itself.

This question and the other short answer one were meant to be a test to see if we could do research under him. It was basically a job application.

 

[not sure]

Hold on. Do your universities actually set tests based on chapters and not expect you to know further material? For us it was more like here is the syllabus, figure it out for yourself. I knew I should have gone to a North American school.

 

[bickelz]

Hold on. Do your universities actually set tests based on chapters and not expect you to know further material? For us it was more like here is the syllabus, figure it out for yourself. I knew I should have gone to a North American school.

Well, yeah [MENTION=3710]kiu[/MENTION], are science tests supposed to cover stuff from upper level classes. They were 333 questions in a 123 class. I actually did figure out the whole chapter by myself too. I literally sat down for 3 hours and learned the whole thing. No reason for me to not get a B yet I wil get a D.

 

[not sure]

Well, yeah [MENTION=3710]kiu[/MENTION], are science tests supposed to cover stuff from upper level classes. They were 333 questions in a 123 class. I actually did figure out the whole chapter by myself too. I literally sat down for 3 hours and learned the whole thing. No reason for me to not get a B yet I wil get a D.

Well that does seem a bit extreme but I suppose you could appeal to your department head or, wait for the result and hope that the bell curve works in your favour.

 

[Nixie]

Yea, I took bonehead chemistry or Chemistry for Non Technical Majors as it was called. F**K science. Never could stand it. Surprising since I am an INTJ. Not that I don't understand it, just don't like it.

I had one econ prof (best evar) who gave us an essay test with like 3 questions. I had a heart attack when I saw the 32 on it. Of course the highest grade was a 36 but yea, he gave tests like that all the time. One of the unspoken things you learn in college is putting up with the crazy ass requirements of the various profs. I had one that would throw your stuff away if you didn't fold it, with the crease facing left and put your name, the class name, the section and time of the class on the top corner.

 

[bickelz]

Yea, I took bonehead chemistry or Chemistry for Non Technical Majors as it was called. F**K science. Never could stand it. Surprising since I am an INTJ. Not that I don't understand it, just don't like it.

I had one econ prof (best evar) who gave us an essay test with like 3 questions. I had a heart attack when I saw the 32 on it. Of course the highest grade was a 36 but yea, he gave tests like that all the time. One of the unspoken things you learn in college is putting up with the crazy ass requirements of the various profs. I had one that would throw your stuff away if you didn't fold it, with the crease facing left and put your name, the class name, the section and time of the class on the top corner.

Lolz wtf?

 

[Blind Bandit]

Go to your department head. it may not do you much good but at least you let someone know about it.

 

[Nixie]

Yea, the rationale from the one prof about folding the papers was that she rubberbanded them together so she could carry them all and I guess she was really anal about the fact that she wanted all the creases facing the same way. It was insane! I actually saw her reach over and pick out a paper that didn't comply and just toss it in the trash all casual like.

edit: Me personally--I wouldn't go see anybody but the prof first.

 

[Blind Bandit]

Yea, the rationale from the one prof about folding the papers was that she rubberbanded them together so she could carry them all and I guess she was really anal about the fact that she wanted all the creases facing the same way. It was insane! I actually saw her reach over and pick out a paper that didn't comply and just toss it in the trash all casual like.

edit: Me personally--I wouldn't go see anybody but the prof first.

In a normal situation i would as well. But I'm pretty sure that will come down to the professor's expressing their right to teach their way. I doubt it will do much good but to push more friction.

Going to the department head or the Dean often gets someone who will actually listen.

 

[Nixie]

Yea, I usually advocate a suck it up mentality and see going to the Dean as whiney. Just saying that is how I would see it--not projecting whininess on you or bicklez.

 

[Blind Bandit]

Yea, I usually advocate a suck it up mentality and see going to the Dean as whiney. Just saying that is how I would see it--not projecting whininess on you or bicklez.

I have to disagree its within his rights as a student.

 

[bickelz]

Yea, I usually advocate a suck it up mentality and see going to the Dean as whiney. Just saying that is how I would see it--not projecting whininess on you or bicklez.

I'm not going to go to the dean. Don't worry [MENTION=3096]Sonyab[/MENTION], I ain't no pussy-ass-bitch. Gator needs his gat.

I have to disagree its within his rights a student.

Yeah, but they'd just laugh at me. It's honestly not a huge deal. As pissed off as I am, this is the final chem class I will be taking. This test was the last straw and the last sign that I need to know that there will be no more science for zach. Unless it's psychology. But nothing physical. It's way too practical for my taste.

Lolz @ my first reaction to those questions.

#1 Shit, I don't know this.
#2 Who cares how you get that solution? It's a hypothetical question anyways.

My only regret other than not being able to answer them is to have the balls to write something sarcastic or a story. It would look funny if I got all the multiple choice ones right and then decided to just not care mid test.

 

[Detective Conan]

I have to disagree its within his rights as a student.

True, but... This:

but they'd just laugh at me.

Unfortunately, a lot of grading in college is final these days. It's mostly because of professors not willing to listen to legitimate complaints of the students, which I can kind of understand, seeing as how they probably have/had to put up with a lot of illegitimate ones, either because of negligence or hard-headedness. However, seeing as it should be the job of the professor to listen to his/her students, I don't think that past experience really matters (sadly, this isn't the case, as most professors in big universities these days are preoccupied with personal research and projects).

 

[nil]

This thread makes me realize something:

There is no way in hell I am majoring in chemistry. This does not sound like shit I want to do.

Also, the thread makes me wary of majoring in either mathematics or physics...

 

[bickelz]

This thread makes me realize something:

There is no way in hell I am majoring in chemistry. This does not sound like shit I want to do.

Also, the thread makes me wary of majoring in either mathematics or physics...

I feel like math is a bit more systematic though. There are rules/patterns in chemistry but every other frickin' problem is an exception to those rules. I actually like math, which is probably why I thought I liked chemistry.

I've heard some crazy shit about multivariable calculus though. Instead of Cartesian coordinates (x,y), you have to learn this whole new system that involves theta and the radius. But calculus is actually creative and is as abstract as it is concrete. You really have to get the big ideas to get calculus. Honestly, I feel like there was a ton of Ne required to invent calculus.

There is actually probably an easy calculation for these problems though, that's what pisses me off. I also hate the lab. Oh [MENTION=3519]nil[/MENTION] if you don't like the lab, don't major in a lab science. I have always felt uncomfortable in the lab so that could explain a lot of stuff. ISTJ science professors are also hard to deal with. Especially if they pronounce "hydroxide" as "hydrocide" and "hydrogen" as "he-dro-hen".

 

[jyrffw54]

you need [MENTION=387]IndigoSensor[/MENTION]

I should probably go unearth my gen chem notes from the dust now...brb