Chemistry Essentials for Dummies

Chapter 13. Ten Serendipitous Discoveries in Chemistry

In This Chapter

· Reviewing some great discoveries

· Examining some famous people of science

Chemistry doesn’t always go as planned. This chapter presents ten stories of good scientists who discovered something they didn’t know they were looking for.

Archimedes: Streaking Around

Archimedes was a Greek mathematician who lived in the third century BCE. Hero, the king of Syracuse, gave Archimedes the task of determining whether Hero’s new gold crown was composed of pure gold, which it was supposed to be, or whether the jeweler had substituted an alloy and pocketed the extra gold. Archimedes figured that if he could measure the density of the crown and compare it to that of pure gold, he’d know whether the jeweler had been dishonest. But although he knew how to measure the weight of the crown, he couldn’t figure out how to measure its volume in order to get the density.

Needing some relaxation, he decided to bathe at the public baths. As he stepped into the full tub and saw the water overflow, he realized that the volume of his body that was submerged was equal to the volume of water that overflowed. He had his answer for measuring the volume of the crown. Legend has it that he got so excited that he ran home naked through the streets, yelling, “Eureka, eureka!” (I’ve found it!).

Vulcanization of Rubber

Rubber, in the form of latex, was discovered in the early 16th century in South America, but it gained little acceptance because it became sticky and lost its shape in the heat. Charles Goodyear was trying to find a way to make the rubber stable when he accidentally spilled a batch of rubber mixed with sulfur on a hot stove. He noticed that the resulting compound didn’t lose its shape in the heat. Goodyear went on to patent the vulcanization process, the chemical process used to treat crude or synthetic rubber or plastics to give them useful properties such as elasticity, strength, and stability.

Molecular Geometry

In 1884, the French wine industry hired Louis Pasteur to study a compound left on wine casks during fermentation — racemic acid. Pasteur knew that racemic acid was identical to tartaric acid, which was known to be optically active — that is, it rotated polarized light in one direction or another. When Pasteur examined the salt of racemic acid under a microscope, he noticed that two types of crystals were present and that they were mirror images of each other. Using a pair of tweezers, Pasteur laboriously separated the two types of crystals and determined that they were both optically active, rotating polarized light the same amount but in different directions. This discovery opened up a new area of chemistry and showed how important molecular geometry is to the properties of molecules.

Mauve Dye

In 1856, William Perkin, a student at The Royal College of Chemistry in London, decided to stay home during the Easter break and work in his lab on the synthesis of quinine. (I guarantee you that working in the lab isn’t what my students do during their Easter break!) During the course of his experiments, Perkin created some black gunk. As he was cleaning the reaction flask with alcohol, he noticed that the gunk dissolved and turned the alcohol purple — mauve, actually. This was the synthesis of the first artificial dye.

Kekule: The Beautiful Dreamer

Friedrich Kekule, a German chemist, was working on the structural formula of benzene, C6H6, in the mid-1860s. Late one night, he was sitting in his apartment in front of a fire. He began dozing off and, in the process, saw groups of atoms dancing in the flames like snakes. Then, suddenly, one of the snakes reached around and made a circle, or a ring. This vision startled Kekule to full consciousness, and he realized that benzene had a ring structure. Kekule’s model for benzene paved the way for the modern study of aromatic compounds.

Discovering Radioactivity

In 1856, Henri Becquerel was studying the phosphorescence (glowing) of certain minerals when exposed to light. In his experiments, he’d take a mineral sample, place it on top of a heavily wrapped photographic plate, and expose it to strong sunlight. He was preparing to conduct one of these experiments when a cloudy spell hit Paris. Becquerel put a mineral sample on top of the plate and put it in a drawer for safekeeping. Days later, he went ahead and developed the photographic plate and, to his surprise, found the brilliant image of the crystal, even though it hadn’t been exposed to light. The mineral sample contained uranium. Becquerel had discovered radioactivity.

Finding Really Slick Stuff: Teflon

Roy Plunkett, a DuPont chemist, discovered Teflon in 1938.

He was working on the synthesis of new refrigerants. He had a full tank of tetrafluoroethylene gas delivered to his lab, but when he opened the valve, nothing came out. He wondered what had happened, so he cut the tank open. He found a white substance that was very slick and nonreactive. The gas had polymerized into the substance now called Teflon. It was used during World War II to make gaskets and valves for the atomic bomb processing plant. After the war, Teflon finally made its way into the kitchen as a nonstick coating for frying pans.

Stick 'Em Up! Sticky Notes

In the mid-1970s, a chemist by the name of Art Frey was working for 3M in its adhesives division. Frey, who sang in a choir, used little scraps of paper to keep his place in his choir book, but they kept falling out. At one point, he remembered an adhesive that had been developed but rejected a couple years earlier because it didn’t hold things together well. The next Monday, he smeared some of this “lousy” adhesive on a piece of paper and found that it worked very well as a bookmark — and it peeled right off without leaving a residue. Thus was born those little yellow sticky notes you now find posted everywhere.

Growing Hair

In the late 1970s, minoxidil, patented by Upjohn, was used to control high blood pressure. In 1980, Dr. Anthony Zappacosta mentioned in a letter published in The New England Journal of Medicine that one of his patients using minoxidil for high blood pressure was starting to grow hair on his nearly bald head. Dermatologists took note, and one — Dr. Virginia Fiedler-Weiss — crushed up some of the tablets and made a solution that some of her patients applied topically. It worked in enough cases that you now see Minoxidil as an over-the- counter hair-growth medicine.

Sweeter Than Sugar

In 1879, a chemist by the name of Fahlberg was working on a synthesis problem in the lab. He accidentally spilled on his hand one of the new compounds he’d made, and he noticed that it tasted sweet. He called this new substance saccharin. James Schlatter discovered the sweetness of aspartame while working on a compound used in ulcer research. He accidentally got a bit of one of the esters he’d made on his fingers. He noticed its sweetness when he licked his fingers while picking up a piece of paper.