February 19, 2017

Homework Help: Chemistry - v/v versus w/w

Posted by annie on Monday, September 20, 2010 at 4:22pm.

Thanks a lot:)

So just to confirm: normally for any chemical bought from manufacturer, if it is not stated, the % usually means v/v? Seems like for conc sulphuric acid, when it is stated 97% sulphuric acid, it means 97% w/w sulphuric acid?

Thank you very much.

Posted by annie on Monday, September 20, 2010 at 10:33am.

I have a bottle of 95% ethanol purchased from the manufacturer.

Normally, when it is not stated, does it mean 95% w/w ethanol?

I need to prepare 100ml of 40% v/v ethanol solution from 95% ethanol.
Please show me the calculation steps.


Chemistry -repost thank you in advance - bobpursley, Monday, September 20, 2010 at 11:01am
when not stated, 95% is v/v

you want to dilute the ethanol 95/45 times, or 2.111 times. THat means one part alcohol, and 1.111 parts water.

100ml/2.111=47.37 is a part.
so, 47.37 ml of 95%
52.63 ml of water.

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