blunt essays with sharp points
Jun 16, 2012 11:40 AM–Bicarbonate gets its name from how it combines with metal atoms, compared to carbonate.
A bicarbonate is a carbonate with a hydrogen atom attached. The hydrogen atom’s one positive electrical charge leaves the carbonate with only one of its two negative electrical charges free.
For example, one carbonate can capture two atoms of a metal, if each metal atom has one positive charge. But it takes two bicarbonates to capture the same two metal atoms. You end up with twice the number of carbonates combined with the same number of metal atoms. Thus the name: bi- (meaning two) carbonate.
You can think of the second carbonate as diluting the metal further, and this is how it often works in practice. For example, washing soda is the carbonate of sodium, and baking soda is the bicarbonate. Because there is more carbonate diluting the sodium in baking soda than in washing soda, the baking soda is weaker.¹
In 19th century writings, you will also find the less precise name “supercarbonate”: super- (meaning above, or higher than normal) carbonate.
In the 21st century, the preferred more precise name is “hydrogen carbonate”. Chemists also prefer to use the pure metal name, such as “sodium” instead of “soda”, because “soda” has multiple meanings.
For example: in old Irish soda bread recipes you will see “supercarbonate of soda”, but on the box of baking soda you will see “sodium bicarbonate” and in modern chemistry books you will see “sodium hydrogen carbonate” – all meaning the same compound.
1. In chemical notation:
2 Na⁺ + 1 CO₃²⁻ → 1 Na₂CO₃ (sodium carbonate, washing soda)
2 Na⁺ + 2 HCO₃¹⁻ → 2 NaHCO₃, (sodium hydrogen carbonate, baking soda)
Labels: atoms, baking soda, bicarbonate, carbonate, charge, chemical equation, chemical formula, chemical notation, chemistry, etymology, hydrogen, metal, nomenclature, soda, sodium, supercarbonate, washing soda, word origin
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