The History of Chemistry

1. The History of Chemistry Wait a minute…that’s too much! How about… The History of Chemistry, Abridged

2. What does Chemistry mean? • In the most general terms, chemistry is the study of chemicals. Chemistry is the science that explains how matter changes.

3. Chemistry is a science about the occult, the hidden, the invisible. No wonder it took so long for chemical secrets to come out…and it all started with fire. For a long time, chemists were considered to be witches…many were burned at the stake only because they understood chemistry.

4. Where did the study of chemistry come from? The very first chemical reaction to impress our ancestors was fire. People discovered chemistry over 50,000 years ago, but they didn’t know it yet. For a long time, chemists were thought to be witches.

5. Fire revealed hidden features of matter. If you heat a piece of wood, all you get is hot wood, at first…but suddenly, at some point, the wood bursts into flame. Where did that come from?

6. Probably the best thing about fire was that it could control other chemical reactions: cooking, for example.

7. You know how scientists are: if they can cook one thing, they’ll cook another. Pretty soon, they were cooking rocks! Scientists are inquisitive…they want to learn; so they experiment. Sounds crazy, but one of the rocks they tried to cook, a green, crumbly rock, melted, changed and became an orange liquid that cooled into shiny, metallic copper!

8. The discovery of copper encouraged scientists to smelt red rocks into iron…bake mud into bricks…saute fat and ashes into soap…and (without fire) to curdle milk into yogurt…ferment grain into beer…and cabbage into kimchee. The next thing you knew, chemistry had cause civilization! Mud brick Smelt iron Fat & ash to make soap Curdling milk to make yogurt Without chemistry, you would still be living in the Stone Age!! “Chemistry” led to many useful inventions and discoveries.

9. What accounts for matter’s secrets? The ancient Greeks came up with at least 3 different theories.

10. The atomists, led by Democritus, thought that matter was made out of tiny, invisible particles, or atoms (a-tom = “no cut’). If you cut and cut and cut and cut, they reasoned, the process had to stop somewhere. People thought Democritus was crazy, but he was actually correct.

11. Another philosopher, Heraclitus, suggested that everything was made out if fire. This theory didn’t last long.

12. But atoms couldn’t be seen, and…fire? I mean, really! The great Aristotle announced that there were actually four elements, or basic substances, from which all else was composed. These were air, earth, fire, and water. Other stuff, he opined, was a blend of these four.

13. Of the three Greek theories, for some reason, it was Aristotle’s theory that most influenced medieval science. His theory actually lasted until fairly recent history! It was so optimistic! If everything was a mixture of four elements, then you should be able to turn anything into anything else just by tweaking the ingredients! Thus, the study of alchemy was born.

14. This hopeless quest was taken up in Persia by Jabir (8th century) and Al-Razi (10th century), who invented all sorts of useful lab equipment and procedures in the process. This proves you can make tremendous practical progress with stupid ideas. Jabir Al-Razi

15. Medieval Europe borrowed the Islamic science - and its name, alchemy (= “the chemistry” in Arabic) - and its hunger for transmuted gold. The German alchemist Hennig Brand for example, tried to make gold by distilling buckets of urine! In the end, Brand’s equipment glowed in the dark…he had discovered phosphorus - but no gold…

16. Despite their wilder speculations, the alchemists accomplished a lot in the lab: they perfected distillation, filtration, titration, etc. They advanced glassmaking, metallurgy, explosives, corrosives…and they invented “fortified wine,” i.e. hard liquor.

17. But alchemists’ lab technique missed one big thing: they failed to collect gases. If a reaction consumed gas, the alchemists had no way of knowing. If it gave off a gas, they let it escape. This meant they could never fully account for the ingredients or products of chemical reactions.

18. The modern study of gases or ”airs” began in the 1600s, with some investigations into the effects of air pressure. Consider this demonstration by Otto Von Guericke (1602-1686).

19. This upside down bottle became a gas collector in the hands of Joseph Priestley (1733-1804), a minister who set up a lab in his kitchen. Priestley’s reactions took place in a sealed flask connected by a tube to an inverted bottle of liquid. (The bottle was immersed in the same liquid.)* The reaction generated gas that would bubble up through the liquid and collect in the bottle.

20. A closer look at Priestley’s experiment.

21. Priestly stored the gases in pig bladders he happened to have lying around the house. He used those bladders of gas in a variety of experiments.

22. For example, when he combined strong acid with iron filings, the reaction produced a gas, or “inflammable air,” that burned explosively. We know it as hydrogen.

23. Another experiment heated a red mineral called “calx of mercury.” As the calx melted, droplets of pure mercury condensed on the walls of the bottle, while gas accumulated in the water bottle. Priestly heated with lenses and sun light to avoid smoky, ashy fires. Priestley noticed that a flame burned brighter when surrounded by this new gas. We know this gas as oxygen.