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Author: Subject: Making multipurpose Stock solutions
Hawk_Eye15
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[*] posted on 2-11-2004 at 13:18
Making multipurpose Stock solutions


Hello, I'm new to the board and am seeking some homework help I am a first semester Biotechnology student.

The part I need help on is making multi-purpose stock solutions with a certain pH and I'm supposed to use hydrocloric acid for the right pH. For example:

One liter of 1M Tris-Cl buffer, ph 6.8

I don't have a buffer table, but the homework includes a list of Formula weights.

The Tris base FW is 121.1

So what I need to know really is if my formula is right. If not could I get a push in the right direction?

Ok so here goes the formula I have come up with,

121.1 g/mol * 1M * 1L

By looking at it I think it is wrong, as I believe you have to add Hydrocloric acid to the solution in order to bring the pH up so you cannot start off with 1L as final volume.

Could someone point out what I'm doing wrong or perhaps point me to a website with some information on it? Sorry about the long post as it is that I haven't worked with Tris buffers as of yet in class.

Thanks!
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Dodoman
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[*] posted on 2-11-2004 at 14:02


Well i won't answer your question. But there is one thing that really bothers me and makes me wonder if you realy know anything about chemistry. How do you intend to bring the pH up by adding HCl ?
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Hawk_Eye15
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[*] posted on 2-11-2004 at 14:51


Thanks for the reply. To be totally honest I know almost nothing about chemistry as I haven't taken that course yet ,which I was going to take but due to some prereq. classes I couldn't yet. But the class I am in is called "Biotechnology Applications" which we really only do solutions, dilutions, calibration of lab equipment and the like.

My Professor says that he doesn't expect us to know all kinds of chemistry and such by the end of the class but rather knowing good laboratory practices, basic calibration of equipment, and keeping up with a lab notebook. He just wants to expose us to some of this stuff for later on ya know?
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chemoleo
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[*] posted on 2-11-2004 at 15:35


Hmm, before anyone bothers with any explanations, I think the originator of this thread really really ought to do some quick and dirty background reading.

For instance have a look at this:

http://www.scientia.org/cadonline/Chemistry/acidbase/titrati...

To be honest I think this quick tutorial willbe much more useful than a dozen replies!




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