10:24am

Wed April 20, 2011
Krulwich Wonders…

Chewing On Carbon: The Celery Question

Once again, the subject is carbon. So far we've been celebrating carbon's ability to bond with other atoms. Today we get violent — and break those bonds.

When you eat a carrot, set fire to a piece of paper, or put a match to a lump of coal, carbon atoms are being yanked, juggled and ripped out of each other's embrace. People have gotten very good at breaking carbon bonds: that's how we light our cities, drive our cars, power our tools. But let's look at this from carbon's point of view...

A couple of quick thoughts: when we break a carbon bond, there's not a sudden pop or release of energy. It's more subtle than that. Carbon, whenever free, immediately hooks up with a new, different set of atoms, and the new relationship is often more efficient, creating a net energy savings over time. Heat that used to be locked up is now released, and that's where we get our energy boost.

The Celery Exception?

But...as I wrote this script, I couldn't help wondering about celery. Yes, celery. We all know a stalk of celery is just water trapped in a hunk of green fiber. You snap off a piece and you chew and chew and chew and chew, and whatever bond-breaking you may be doing is going to pale beside the energy you put into biting and chewing. That's why celery is used in weight loss diets; it probably costs you more energy than you get. This is just to remind you, not every act of carbon-breaking "releases" extra energy. (Give a hungry man nothing but an endless supply of celery and a few weeks later his jaws will be rippling with muscles, but I suspect he'll be dead — of starvation. I don't know this for a fact. I've just always suspected that celery is more an exercise tool than a food.)

Tomorrow — Carbon in Love! Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.