Coefficients and Subscripts for Chemistry Dummies

Coefficients and subscripts in a formula

Anyone out there remember The Car Guys? Tom and Ray Magliozzi? For a couple of decades, the Boston-based brothers had a weekly talk show on public radio called "Car Talk." The two (both of whom had BS degrees from M.I.T.) often poked fun at art history majors... and guess what? Today's DotD candidate actually has a PhD in art history (or so she claims: it's eHow.com, so who knows?)! We kinda wondered, though, just what Teresa J. Siskin was doing attempting to explain the "Difference Between a Coefficient and a Subscript" at Sciencing.com.

We'll start right off by pointing out that although both "coefficient" and "subscript" have general meanings in science and mathematics, Siskin didn't bother with those definitions. Instead, she jumped straight to chemistry, where she defined the two by telling her readers,

"Coefficients and subscripts are essential components when writing longhand chemical formula compounds or equations. A coefficient, reflecting the number of molecules in a given substance, is a number placed in front of a given molecule’s abbreviation. A subscript, however, reflecting each element’s atomic contribution to a given molecule, appears following or between elemental abbreviations and is typically smaller in size and set below the type line."

That's more or less correct, although rather wordy. We do need to point out that chemists call those letter combinations a chemical symbol, not a "molecule's abbreviation," though. What happens next, however, is not more or less correct... Part of that is the fault of the lazy programmers at Demand Media Studios¹ and part of it is Teresa's obvious unfamiliarity with things scientific in general and chemistry-related in particular.
You see, Siskin decided to give an example, using good old dihydrogen monoxide, aka water:

"The chemical equation for creation of water molecules, or H2O, is one that uses coefficients. In this equation, two molecules of hydrogen, or 2H2, bond with two molecules of oxygen, or 2O2, to yield two molecules of water, or 2 H2O... this reaction, written completely as 2H2 + 2O2 = 2H2O, shows that hydrogen and oxygen must be present in equal proportions to maximize the amount of water molecules produced,"

Well, Teresa, no... the equation doesn't show anything of the sort. First off, the formula for water isn't H2O, it's H₂O. Second, that bull about two molecules of H₂ and two molecules of O₂  yielding 2H₂O? Count the atoms, and you'll learn that doesn't balance: see, your formula (which is in reality 2H₂ + O₂ → 2H₂O ) leaves a couple of oxygen atoms wandering around loose. Oh, and we have no idea what that rubbish about "maximize" is about.

We pass out a new award every day, as often as possible to freelance writers who we catch "talking through their hats." For the failure of someone – Teresa herself, some woefully unqualified "fact checker" cum content editor, or both – to understand what was written, we do hereby bestow the Dumbass of the Day upon Siskin. After all, she could have proofread the stuff...

¹ DMS, as in "You can't spell 'dumbass' without 'DMS'!" The programmers apparently never bothered to find out about the <sub> tag...

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