averaging the titres in titration (1 Viewer)

[midnight_magick]

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

 

[richz]

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

 

[serge]

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

its not always a 'test run' but if its way off then yes discard it

 

[mitochondria]

We are always tempted to discard the results that are waaaaaay off (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.

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? Surely you can't estimate to the nearest 0.01mL on a burette...

 

[xvelidras]

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 . 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]

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]

Apparently, you're supposed to make 10 other divisions in each 0.1ml division, for improved accuracy . 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) 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?