Concentrations in Percent (v/v)

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cortinator
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Concentrations in Percent (v/v)

Post by cortinator » Thu Jun 17, 2010 12:47 am

"Describe how to prepare 50 ml of 75% ethyl alcohol when your only source is a stock container of 95% ethyl alcohol."

Help! I have no clue what this means.

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JackBean
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Post by JackBean » Thu Jun 17, 2010 9:27 pm

the 50 ml contain 0.75*50ml of pure ethanol. This you take from the 95%, so you must divide it by 0.95
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

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canalon
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Post by canalon » Thu Jun 17, 2010 9:29 pm

Ci x Vi = Cf x Vf
This is all you need. i stand for initial, f for final.
So you know the final volume and concentration, and knows the the initial concentration, so plug the numbers and solve for the initial volume.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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