|MadSci Network: Chemistry|
For some purposes, the only difference between washing soda (sodium carbonate)
and baking soda (sodium bicarbonate) is that washing soda will consume two
equivalents of acid, while baking soda will only consume one equivalent.
However, for other purposes they are distinct. Removing the second proton from carbonic acid (H2CO3), to form washing soda, takes more oomph than removing the first--which forms baking soda. Since these reactions are reversible, this means that washing soda is a stronger base than baking soda, and in fact is considered a caustic (which means that, among other things, you DON'T want to use it for baking!) If you rub a little washing soda on your hands, then rinse it off, your hands feel soapy; baking soda doesn't do that, and the reason is that baking soda is too mild a base.
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