Acid Rain for Dummies

Carbon dioxide and rain water, acid rain, pH

You've heard of acid rain, right? You haven't? Well, rain that picked up pollutants from industry and power plants in the Midwest became acidic and started eating away at famous buildings and monuments on the east coast of the US, which was a driving force behind amendments designed to strengthen the Clean Air Act of 1963 during the 1970s. With that in mind, would it surprise you to learn that rain is naturally acidic? This little revelation apparently surprised Robert Balun of eHow.com, when he attempted to explain "Why Is Rain Naturally Acidic?" at the niche site Sciencing.com.

Balun's background for this piece is his BA in History; a degree carefully structured to avoid ever taking "difficult" courses like math or science where there are objective answers instead of opinions. That omission is probably why Robert showed how confused he was about acidity in his introduction:

"Pure water is neither alkaline nor acidic. As rain falls from the atmosphere the impurities it collects changes the pH of the rain water, making it slightly acidic. The pH of water determines if it is acidic or alkaline."

Robert, Robert, Robert: you have that relationship backwards: the pH of water doesn't "[determine] if it is acidic or alkaline," it's merely a measurement that indicates whether something is acidic or alkaline, not causes the acidity or alkalinity.

Robert then went on to a fairly well-done copy-reword-paste job on the definition of pH, followed by his version of explaining how rainwater gets a low pH: "Rain water collects impurities as it falls from the atmosphere. One of these impurities is atmospheric carbon dioxide, or CO2, which is a weak acid." Well, no, Robert: carbon dioxide gas isn't a weak acid. Carbon dioxide dissolved in water makes a weak acid, carbonic acid to be precise. Perhaps if you had understood the term "equilibrate" in your reference you would have gotten that right. Whether one would consider dissolved CO2 an "impurity" is another question... Balun continues by explaining that "...most rain water ultimately has a pH between five and seven, making it slightly acidic."

...although almost every reference we saw suggests that the pH of rain water is normally about 5.6, which is, we suppose, "between five and seven." Oh and by the way? The all-holy AP Stylebook's instructions about numerals notwithstanding, pH values are never spelled out, because pH is "a dimension" (apparently, the book's writers also have BA degrees).

Robert finished with a discussion, of sorts, of those "impurities" he mentioned before, and a bunch of rubbish on acid rain, Why, we don't know, but probably because he didn't have enough words to meet the DMS minimum. That's why he went all historical on us with an overly wordy answer that, frankly, wasn't quite right. And that's also why he's the Antisocial Network's Dumbass of the Day.

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