Why do we add NaHCO3 when testing carboxylic acids?
Hi Bill C At the level you are studying there are only 2 organic substances which are acidic so you need to find out which one you have. This is how you would normally do it :- 1 Dissolve the unknown substance in water and test pH. Gives acid pH 2 To this solution add solid Na2CO3 or NaHCO3 ——– if it fizzes[CO2] then the substance is a carboxylic acid RCOOH ——– if it doesn’t fizz it is a phenol [ OH attached directly to a benzene ring] Why Does one fizz and other one doesn’t ? ANSWER They are both weak acids [ compared to say HCl] but carboxylic acids are strong enough to liberate CO2 and phenols are not strong enough. To put it a different way —- carboxylic acids are stronger than H2CO3 [the acid corresponding to Na2CO3] and so liberate the CO2 whereas phenols are weaker than H2CO3 and can’t liberate CO2.
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