1. What was phlogiston? Based on what theoretical and experimental bases did Lavoisier reject it? (68)
Phlogiston is a substance that was once believed to be in all combustible materials. The phlogiston theory originated in Ancient Greek around 1667 by Johann Joachim Becher, a German physician who pursued alchemy. The purpose of this theory was to help explain why materials turned to ash after burning and why the break down of metals through rusting. The phlogiston theory states that flammable materials all contain two different substances called phlogiston and calx. During the process of burning the phlogiston would escape in the form of a gas into the air and the calx would be the leftover material also know as dephlogisticated substance. This phlogiston theory help explain different events that occur during burning. The phlogiston would escape the flammable material in the form of smoke into the air, while the dephlogisticated substance would be the ash that remained after the burning process. Unfortunately we know this to not be true and there were many problems with this theory. If the burning process was to cause lose of phlogiston then during the burning the material would slowly lose weight but this was not the case for all flammable materials. Some believed that phlogiston had negative weight, which was illogical to Lavoisier. This experiment help convince Lavoisier that the phlogiston theory was flawed. He believed that combustion relied on a substance with weight so he introduced ‘oxygen’. He proved his belief by weighing closed vessels while combustion occurred. He showed that the oxygen combined to the metal and at the same time disproved the belief that phlogiston had negative weight. This was an astonishing accomplishment by Lavoisier at the time and he used his oxygen theory to help create a modern chemical system of his time.
2. Explain the chain of discoveries that finally led to the invention of the electromagnetic...
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