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Law and Chaos (1640-1665). CM1100 History of Chemistry: Gases and the Gas Laws. Ancient Beliefs. Matter made up of 4 ELEMENTS: Air, Earth, Water, Fire. 4 Qualities: Hot, Cold, Moist, Dry Nature abhors a vacuum Aristotle.
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Law and Chaos(1640-1665) CM1100 History of Chemistry: Gases and the Gas Laws
Ancient Beliefs • Matter made up of 4 ELEMENTS: Air, Earth, Water, Fire. • 4 Qualities: Hot, Cold, Moist, Dry • Nature abhors a vacuumAristotle
Galileo’s Laboratory (1638-43) • Galileo had questioned why a suction pump could only raise water in a mine by about 9-10 metres. • Torricelli, his secretary, proposed an experiment performed by Viviani in 1643 (after Galileo was dead) to prove that the effect was caused by atmospheric pressure. • Nature does not abhor a vacuum!
Weight of the Atmosphere • Viviani took a 2.5m long glass tube and filled it with mercury and inverted it into a bowl of mercury. • Mercury is 13.6 times denser than water and the mercury column rose to about 76 cm. • A vacuum was created at the top of the tube
The Barometer(Gk “baros” for weight; “metron” for measure) • The column of mercury rose and fell depending on the weather • The weight of the column of mercury was equal to the weight of the air • The type of experiment had been performed with water some years before in Rome
Pascal and Périer (1648) • Torricelli wrote a letter explaining his findings on atmospheric weight. It eventually reached Blaise Pascal in France. • He instructed Florent Périer, his brother in law, to make measurements with a mercury barometer at the bottom and top of Puy de Dome (an extinct volcano, 1.5m high) in the Massif Central • The experiment showed that the pressure of the atmosphere decreased with height.
van Helmont (1579-1644) [yet another famous Belgian!] • He believed that Air was the basis of all matter • He coined the word GAS (Gk “khaos” for empty space) as the product of some chemical reactions e.g charcoal burning
Gas Sylvestre (Gas from Wood) • We know this gas today as CARBON DIOXIDE. • van Helmont’s work (published after his death in 1648) indicated that it was produced not only from burning charcoal but also from spa water, fermenting wine and eructions.