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averaging the titres in titration (1 Viewer)

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hello, i have another question lol
when you average the titre readings from the table do you
* skip the first reading because it is always a test run and therefore inaccurate, and;
* use only the readings that are within 0.2mL of each other, using only 3 of these readings in calculating your average?
i'm confused as i have been told so many different ways in doing this from friends, tutoring, teachers.....
thankyou all :D
 

richz

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acutally just get 3 values that are within +- 0.01ml of each other, and take the avg of them
 

serge

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midnight_magick said:
hello, i have another question lol
when you average the titre readings from the table do you
* skip the first reading because it is always a test run and therefore inaccurate, and;
* use only the readings that are within 0.2mL of each other, using only 3 of these readings in calculating your average?
i'm confused as i have been told so many different ways in doing this from friends, tutoring, teachers.....
thankyou all :D
its not always a 'test run' but if its way off then yes discard it
 

mitochondria

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We are always tempted to discard the results that are waaaaaay off :p (obviously something has gone very wrong if we are talking about 10mL...)

However, if it's a matter of ~1-2 mL and you only have 3 results you should ALWAYS average all 3 of them. You can't justify that the first result (the slightly off one) is wrong just because the other two results agree with each other. ;)

xrtzx said:
acutally just get 3 values that are within +- 0.01ml of each other, and take the avg of them
Have you come across instruments that dispense 0.01mL titres with high percision? :p Surely you can't estimate to the nearest 0.01mL on a burette...
 
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xvelidras

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mitochondria said:
:p Surely you can't estimate to the nearest 0.01mL on a burette...
Apparently, you're supposed to make 10 other divisions in each 0.1ml division, for improved accuracy :p. Within 0.01ml of each other is just plain crazy, 0.05ml is fine, but for the purposed of high school titration, and not titration comp/olympiad we just take readings to 0.1ml since (at least in public schools) we only have B grade burettes
 

bassqueen16

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lol b grade burettes, yea i know what u mean- i went in the titration comp this year and we got brand new bulbs, and a tiny bit from mine fell into the very tip of my pipette, so nothing was coming out! So i ended up frantically grabbing a pin and popping it out, it took me forever to set up again though cos i was so messy getting the dam thing out lol
 

mitochondria

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svelidras said:
Apparently, you're supposed to make 10 other divisions in each 0.1ml division, for improved accuracy :p. Within 0.01ml of each other is just plain crazy, 0.05ml is fine, but for the purposed of high school titration, and not titration comp/olympiad we just take readings to 0.1ml since (at least in public schools) we only have B grade burettes
Nooooooo, those are A-Grade burettes ;) (Or so I think...)

Now here's my comeback (even though I may be wrong) :p Well! There is a certain error margin on all burettes (because nothing is perfect). I can't remember what exactly it is but I'm sure it's between 0.02-0.05 mL. I guess, then, estimating to the closest 0.01 mL doesn't make much sense ;)

Besides, I believe the smallest point that most people can see is ~0.4mm, so 10 divisions would mean... 4mm O____o

Shall I add touché? :p
 

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