titration prac (1 Viewer)

[Mon]

Besides things like subjectiveness, can anyone help me answer this:
explain why an investigation is best undertaken individually or by a team
thanks

 

[kini mini]

In answering this question you must make very specific reference to the actual prac.

For a titration prac, the advantage of working in a team is efficiency. Teams of two are ideal as one can do the prac whilst the other prepares the next sample. They can then change places, the first records the results then prepares another sample, and so on until you run out of time or reagents.

I can't see much of an advantage in working alone apart from avoiding the problem of subjectivity in measuring results. I don't even think that this should be an issue in a titration though, all you have to do is make readings from accurate instruments such as a burette.

 

[marsenal]

I find that an extremely useful thing about having two people is that it's easier for one to swirle/shake the flask, while the other is letting in the solution from the burette. Otherwise it doesn't really matter in my opinion.

 

[kini mini]

Originally posted by marsenal
I find that an extremely useful thing about having two people is that it's easier for one to swirle/shake the flask, while the other is letting in the solution from the burette. Otherwise it doesn't really matter in my opinion.

My chemistry teacher wouldn't have liked that at all

It's quite possible to do both and get great results.

 

[marsenal]

True, but this way in case one guy dozes of for a second and doesn't realise they're supposed to close the tap there aint a problem (not as big a problem anyway). although if you do a sufficient number of trials it wont matter if the person does doze of once or twice.

 

[JUB JUB]

ahem

hmmmm MON!
I think this is one for STEPHEN-don't you?




muhahahaha


p.s
[E.B 4 H.R.W]

 

[CHUDYMASTER]

I don't think you should ever mention subjectivity in a question like that. It's got NOTHING to do with the experimental procedure. What marsenal said was correct however. It is much wiser to have one person swirling whilst the other person reads the volume, since it is hard to focus on a colour change and a reading at the same time. Therefore, 2 people is better than 1.

 

[kini mini]

Originally posted by CHUDYMASTER
What marsenal said was correct however. It is much wiser to have one person swirling whilst the other person reads the volume, since it is hard to focus on a colour change and a reading at the same time. Therefore, 2 people is better than 1.

Why on earth do you need to focus on the burette during a titration? You turn the tap on full blast until a few ml before your rough endpoint, you shouldn't even need to more than glance at what you're swirling because you know you're nowhere near the endpoint. Left hand on tap, right hand swirling. At the end, you carefully manipulate the tap so drips or only a very small stream of reagent go into the conical flask, you should do this purely by touch as you can see the stream when you're looking at the flask as you swirl it.

Making that argument for such a division of labour in a titration is suicide.

 

[CHUDYMASTER]

Ahh Kini mini, your logic is sound, but ultimately flawed.

You need to observe where exactly the end point occurs by looking at the increments. if the person goes a tad overboard it's okay because the person swirling will call to the reader and that will signal him to stop the burette and make a reading.

Hehe, nah, I guess it depends which way you look at it, both perspectives are valid IMO.

Btw, is that question in the syllabus??

 

[kini mini]

Originally posted by CHUDYMASTER
Ahh Kini mini, your logic is sound, but ultimately flawed.

ROFL!

You need to observe where exactly the end point occurs by looking at the increments. if the person goes a tad overboard it's okay because the person swirling will call to the reader and that will signal him to stop the burette and make a reading.

Hehe, nah, I guess it depends which way you look at it, both perspectives are valid IMO.

Btw, is that question in the syllabus??

I don't know if it is explicitly mentioned in the syllabus, but it certainly could be asked as a matter of experimental procedure.

I fundamentally disagree with you on the measurement of results. You know you have reached the endpoint when there is a colour change, however light, in the flask. You can then look at the burette at your leisure. Notice I don't mention stopping the burette, because you should be adding tiny drips by this stage and so there isn't anything to stop. Your method not only guarantees a greater error because the swirler has to call out to the reader, allowing more solution to flow, but the reader has to take a reading in an instant or else have a punt on the excess volume - another source of error. This element of subjectivity defeats the entire purpose of doing a titration, one of the few school experiments that can produce good results.

If I were marking practical skills, I would fail anyone who wrote what you did. Sorry to sound harsh, but there are no two ways about this one.

 

[CHUDYMASTER]

Well you mention "subjectivity" but either way subjectivity will be a factor because OBSERVING a colour change is highly subjective and so your endpoint is going to be exceeded by miles either way.



Never the less, I end this debate by saying, Good day! *runs off quickly*

 

[speed_bump]

Why stop at 2 people, i feel when doing the prac side of things that 5 people is the ideal team amount.
1 to turn the tap on the burette, 1 to turn swirl the flask, one to watch the burette, 1 to hold a piece of paper under the flask, and one to make sure the person that is turning the tap does so at the right time.
But that might just be me, im not sure.

 

[ND]

Originally posted by speed_bump
Why stop at 2 people, i feel when doing the prac side of things that 5 people is the ideal team amount.
1 to turn the tap on the burette, 1 to turn swirl the flask, one to watch the burette, 1 to hold a piece of paper under the flask, and one to make sure the person that is turning the tap does so at the right time.
But that might just be me, im not sure.

You forgot about the person to cover the top of the burette to stop the reaction with the air.

 

[speed_bump]

not to mention the waterboy

 

[Constip8edSkunk]

...and a cheerleader too.

 

[CHUDYMASTER]

LOL! Come now, I thought this debate ended with 1/2 people!

Come to think of it, we didn't even put a paper with a cross on it under the conical flask. It's pretty useless seeing as though observing a colour change is JUST AS SUBJECTIVE as observing the cross "disappear" when really it shouldn't disappear, it should merely fade.

 

[blingbling]

hi everyoneee... im having so much trouble with the titration prac would anyone be able to send me a titration prac with an aim, method and results pleasse
much appreciated if u can

 

[michaelhazan]

ne one have past titration, or any acids and bases prac exams?