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Joseph Priestly and Antoine Lavoisier. From Phlogiston to Soda And the Founding of Chemistry. Joseph Priestly. British Priest, began dabbling in science after meeting Benjamin Franklin Became interested in the air that floated over fermenting grain at the local root beer brewery
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Joseph Priestly and Antoine Lavoisier From Phlogiston to Soda And the Founding of Chemistry
Joseph Priestly • British Priest, began dabbling in science after meeting Benjamin Franklin • Became interested in the air that floated over fermenting grain at the local root beer brewery • Figured out you could extinguish a candle with the gas that was lighter than normal air • Bubbled the gas through water and found it tasted terrific!
Other Cool Things • Put a plant and a lit candle under a container • Candle went out • Why? • Later, he was able to light both the candle and keep a mouse alive (fewer rules about animal cruelty) • What famous reaction explains this result?
Got Gas? • Mercury (II) oxide • Placed in a sealed chamber • Heated with a magnifying glass • Produced a gas that helped the candle burn brighter • Named it dephlogisticated air
Phlogiston? • What is fire? • Four key observations: • Wood gets lighter when burned • Things cannot burn if there isn’t enough air • Metals turn into a powdery substance when burned • Metal ores (similar to powdery product from burning metals) turn into shiny metal when they are burned with charcoal • When you burn wood or a metal, phlogiston leaves • When you burn a metal ore in a fire, phlogiston returns • Charcoal must be rich in phlogiston, it burns extremely well
Dephlogisticated Air? • Because it was known that air was required for things to burn, Phlogiston theory needed to explain why • Air has a limited capacity for Phlogiston, when it was full, air was said to be Phlogisticated (Like the air from the root beer brewing tanks) • Air that could accept Phlogiston was Dephlogisticated air.
Priestly Meet Lavoisier • Priestly was able to prove that green plants were producing the same gas produced by Mercury (II) oxide • Sent findings to Antoine Lavoisier • Lavoisier was interested
The conflict? • At least three people discovered “Dephlogisticated Air” around this time. Who would get the credit? • First to discover? • First to understand? • Lavoisier began a revolution in science, founded chemistry • Meticulous measurements • Systematic chemical nomenclature • Definition of an element (Water is out!) • Law of Conservation of Mass • When Lavoisier presented his findings, Phlogiston theory died • Just for good measure, they threw a book burning to celebrate