|MadSci Network: Chemistry|
"Bi" is derived from the Latin "bis", meaning "twice". The bi in bicarbonate, refers to the fact that it takes twice as many equivalents (or moles) of bicarbonate ions to neutralize an acid compared to carbonate ions. The same reasoning applies to bisulfate, bisulfite, etc. These anions were also referred to with "acid" nomenclature. For example, sodium acid sulfate. The preferred nomenclature now is "hydrogen", as in sodium hydrogen sulfate. Webster's New Universal Unabridged Dictionary, Simon & Schuster, 1979
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