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Topic: General titration questions  (Read 4054 times)

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Offline whackamole

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General titration questions
« on: August 03, 2012, 10:17:16 PM »
I'm looking to titrate a weak base as accurately as possible with the tools I have at hand.

I have at my disposal:
a 3 place (0.001g) balance with glass doors
50ml burette with 0.1ml divisions
25ml burette with 0.1ml divisions
1ml pipette with 0.01ml divisions
Various other pipettes from 2ml to 50ml with 0.1ml to 0.2ml divisions
Various volumetric flasks and graduated cylinders from 25ml to 1000ml
0.1N H2SO4

1st Question:
How accurate is prepackaged 0.1N H2SO4 purchased from a namebrand chemical supply company?
+/-0.01? +/-0.02? +/-0.03?, etc.

2nd Question:
I understand that to get the most accurate known base, the base will have to be standardized against dried KHP.
If I were to skip that step and purchase prepackaged standardized 0.01N NaOH, how accurately would I be able to standardize the H2SO4?
I'm assuming only to the same significant figure as the NaOH, but I could be wrong. See 1st question.
Along those same lines, would using a standardized 0.313N NaOH solution be more accurate than 0.1N or 0.01N?

3rd Question:
Back to most accurate and maximum number of significant places.
Using the tools at hand and KHP dried as best as possible (I have an oven but not a dessicator to cool it in) to standardize my base, how many significant figures could I realistically expect to achieve?

4th Question+:
I can get KOH or NaOH to use as a base from 0.01N and up.
Which is preferable to use and why?
I've read that NaOH is unstable and can drift on a daily basis.
Is KOH any more stable?
Once I unseal the bottle it's packaged in, how rapidly and how far will it drift in concentration if I keep the bottle capped as much as possible?
Will the very first use and introduction of outside air/humidity cause a significant shift?

I appreciate any time or patience spent in helping me get a better understanding of this, as I'm sure the answers will most likely lead to more questions.
 ???  ;D

Offline Arkcon

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Re: General titration questions
« Reply #1 on: August 04, 2012, 07:41:26 AM »
I'd like to take you questions one at a time, but to start with, I'd like to know more about what you're attempting.  The 0.1 NaOH that you have, is it standardized by the manufacturer for analytical use?  That is to say, is it titrated to a NIST standard (or other national standard) and in the usage date?  Or is it not standardized analytical grade?

What level of accuracy do you need?  You originally put this post in the High School sub-forum.  Is this actually a high school assignment, and you're asking how the significant figures, and accuracy carry over?  Or do you have a need to report a certain amount of accuracy for some industrial purpose?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Borek

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Re: General titration questions
« Reply #2 on: August 04, 2012, 02:39:20 PM »
How accurate is prepackaged 0.1N H2SO4 purchased from a namebrand chemical supply company?

Simple answer: this information should be printed on the label.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline whackamole

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Re: General titration questions
« Reply #3 on: August 04, 2012, 07:58:55 PM »
Thanks for the move and the steerage, Arkcon and Borek.
I don't know why I didn't think to ask the maker first.
Yes, it's standardized AR grade.
Although it's not printed on the label, their website has a C of A traceable to a tritrated NIST standard.
Thanks! That answers most of my questions.

To answer your question, Arkcon, it's not a school assignment.
It's just that this seemed like such basic questions that it belonged at the High School level.
My interest is part work and part hobby.
For work I don't need anything that accurate, but I like to learn as much as I can and how far I can go.

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