In all likelihood the formed sodium isopropoxide (sodium 2-methylpropoxide) is ‘salting out’ the 91 % IPA, that is: it’s driving out the water,
explaining the layers. At the same time the isopropoxide is hydrolysing to NaOH due to the water. It’s also possible that the sodium is reacting
preferentially with the water, thus forming NaOH (which then salts out the IPA). Pure IPA isn't soluble in water with high salts contents...
To answer your previous question about the suitability of 91% IPA, in short; ‘NO!’
But you can repeat the experiment in a meaningful way as follows: look up ‘salting out IPA’ (or similar terms): there are plenty web pages that
detail how to convert 91% IPA to almost 100% IPA by adding lots and lots of NaCl to it. The salt ‘pulls’ out the water leaving you, after
filtering usually, with quite pure isopropyl alcohol.
Next, instead of dunking a whole nugget into the alcohol, cut a neat piece, totally free of skin and protective oil and see how it reacts and whether
you’re getting a clean, clear solution of sodium isopropoxide in IPA. Any oil would probably emulsify into the alcohol, creating deceptive
results…
Alternatively, use any dry alcohol: methyl, ethyl, propyl…
Salting out IPA:
http://www.instructables.com/id/How-to-Salt-Out/
[Edited on 27-4-2011 by blogfast25] |