Organic synthesis
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I want to ask a question about the polar (aqueous) and non-polar (organic) solvents. If I mix sodium hydroxide with alcohol and with another organic solvent (light petroleum, for example) in which solvent does the sodium hydroxide dissolve?
What is the proper solvent to extract sodium bicarbonate from soap and why?
Also please can you suggest a method to determine the total alkali in soap?
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Igloo writes ...
The sodium hydroxide would dissolve (slightly) in the polar solvent, ethanol, but certainly not as well as it would have done in water. Sodium hydroxide would be almost totally insoluble in light petroleum.
Water would be a good solvent to extract sodium bicarbonate from soap. This is because sodium bicarbonate, which contains ionic bonding, is fairly soluble in water (a very polar solvent).
Any free alkali present in soap can be estimated by titrating a known mass of soap (dissolved in water) with a standard solution of an acid such as hydrochloric acid. I’ll leave you to fill in the practical details.
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updated: 02 November 2008
