Predicting the Chemistry inside a Cell

The process of scientific discovery is something like a walk near Freswick Castle. 1 assume you ve never been there. (Neither have 1, but a friend has.) Freswick Castle stands at the end of Scotland s northeast end, at the mouth of the Burn of Freswick in the district of Caithness. As of this writing, it is unlisted in Google Maps, and 1 had to manually scan the coast to find it. Outside the castle is a simple, unlabeled structure that doubles as a biochemical parable. 

Let s approach this as a scientist, with measurement. From the castle side, this structure resembles the circular stump of a roofless tower, eight feet tall and twice that wide. The stones are ancient sand, compacted and weathered, stained different shades of red from iron deposited millions of years ago, but the mortar is new. 

The architect of this singular structure wants you to discover it this way. (I hope I don t subvert his purposes too much by publishing them here—if you happen to see 

1 A view of the entrance to the sculpture efcfco by Roger Feldman, Freswick Castle, Scotland. 

Every one of us stumbles across mysteries in nature. Before Darwin, William Paley told a famous story of discovering a watch in the grass of an English meadow. Paley said finding life is like finding that watch. Here we have the same island and metaphor, but with very different implications. 

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Electrochemical cells are familiar—a flashlight operates on current drawn from electrochemical cells called dry cells, and automobiles are started with the aid of a battery, a set of electrochemical cells in tandem. The last time you changed the dry cells in a flashlight because the old ones were dead, did you wonder what had happened inside those cells Why does electric current flow from a new dry cell but not from one that has been used many hours We shall see that this is an important question in chemistry. By studying the chemical reactions that occur in an electrochemical cell we discover a basis for predicting whether equilibrium in a chemical reaction fa-... 

Continue to look around inside the ekko cell and, in lesser amounts, you ll see metals dissolved and floating around. In fact, you ll see a peculiar pattern of particular metals lots of manganese ions but only a few coppers. This pattern comes about because of chemistry. The columns of the periodic table predict which metals you ll see (and how much of each). For one thing, you won t see much gold, because the cell works very hard to keep gold out. 

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