tips for volumetric analysis


by smart_worker
Tags: analysis, tips, volumetric
smart_worker
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#1
Feb20-14, 06:57 AM
P: 99
guys today i have my chemistry practicals.i have to do titration.i have to suck the pipette with my mouth.it is a rule that everyone must use their mouth only.it is very difficult for me to suck in exact 20ml of the solution and pipette out.so i am not getting the exact titre value.are there any shortcuts to find the titre value.
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Borek
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#2
Feb20-14, 07:05 AM
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You don't "suck exactly 20 mL". You suck more, use your finger to close the pipette, then you let the excess to drop out till the pipette is filled exactly to the mark.
gravenewworld
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#3
Feb20-14, 07:49 AM
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Utterly ridiculous that in 2014 people are still being taught to mouth pipette. I thought this practice was prohibited almost everywhere.

Borek
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#4
Feb20-14, 09:25 AM
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tips for volumetric analysis


Quote Quote by gravenewworld View Post
Utterly ridiculous that in 2014 people are still being taught to mouth pipette. I thought this practice was prohibited almost everywhere.
Sorry to say that, but you are just showing your ignorance - not every part of the world is rich enough.
PhysicoRaj
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#5
Feb20-14, 10:00 AM
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Quote Quote by smart_worker View Post
are there any shortcuts to find the titre value.
You can't decide the concentration of a solution while looking at it. And you are not allowed to do more than that. One shortcut is to get to know the titre value first!
In my case the error was always due to leftover distilled water in the flask. It diluted the pipetted solution and I purposely used to take 0.1mL less than the observed titre value. It worked well for me!
gravenewworld
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#6
Feb20-14, 01:14 PM
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Quote Quote by Borek View Post
Sorry to say that, but you are just showing your ignorance - not every part of the world is rich enough.
Yup, so expensive

http://www.sciencelabsupplies.com/Pi...iller_Red.html


If you can afford to do chemistry, afford chemicasl, afford to have a lab, and afford glassware you can afford minor safety items that can prevent major injuries. Hey mouth pipetting, what a great way to get hepatitis or oral acid/base burns!
Borek
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#7
Feb20-14, 01:54 PM
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You are still not understanding the reality - this kind of safety is considered a luxury in many places. When GDP per capita is 50 times lower than in US, $5 is a serious expense.

And - without getting into details - OP doesn't live in US.


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