Molecular Mondays are a special series here on Planet Pailly about the atoms and molecules that make up our universe, both in reality and in science fiction. In the last two Molecular Monday posts, we looked at the relationship between oxidation and reduction (Oxidation, Part 1) and the purpose of oxidation states (Oxidation, Part 2). Today, we turn our attention to:
Meet an oxidant: a chemical substance that really wants to obtain more electrons.
Also, meet a reductant: a chemical substance that wouldn’t mind losing a few spare electrons.
When these two substances combine, the oxidant will oxidize the reductant, and the reductant will reduce the oxidant. Because oxidation and reduction always occur together, the combined reaction is called a redox reaction.
But not all redox reactions are created equal. Some are more energetic than others.
Just how eager two substances are to oxidize and reduce each other can be quantified in terms of reduction potentials. A high reduction potential indicates that a substance really, really wants to gain electrons. A low reduction potential means a substance would be quite happy to lose some electrons.
I won’t go into how chemists determine the reduction potentials of individual substances, but I will point out that reduction potentials are measured in volts. As I currently understand it, the greater the difference between the reduction potentials of two substances, the greater the voltage will be when those substances react.
This, I think, is a pretty good hint as to why living cells use redox reactions for their energy production. Within the context of science fiction, understanding redox chemistry and the significance of reduction potentials can help in the imagining of both futuristic technology and extraterrestrial biochemistry.
This is my final post on redox reactions, at least for now. I won’t pretend that I fully understand redox reactions, nor will I pretend that I’ve fully explained them in these last few Molecular Mondays posts. But I am convinced more than ever that studying this topic is of immense value for science fiction writers like myself.