Working Students Essay

16330 WordsMar 11, 201266 Pages
Hydrogen Discovery of Hydrogen: A favorite school chemistry experiment is to add a metal such as magnesium to an acid. The metal reacts with the acid, forming a salt and releases hydrogen from the acid. The hydrogen gas bubbles up from the liquid and students collect it in small quantities for further experiments, such as the 'pop-test.' The first recorded instance of hydrogen made by human action was in the first half of the 1500s, by a similar method to that used in schools now. Theophrastus Paracelsus, a physician, dissolved ironin sulfuric acid and observed the release of a gas. He is reported to have said of the experiment, "Air arises and breaks forth like a wind." He did not, however, discover any of hydrogen's properties.(1) Turquet De Mayerne repeated Paracelsus's experiment in 1650 and found that the gas was flammable.(2) Neither Paracelsus nor De Mayerne proposed that hydrogen could be a new element. Indeed, Paracelsus believed there were only three elements - the tria prima - salt, sulfur, and mercury - and that all other substances were made of different combinations of these three. (3) (Chemistry still had a long way to go!) In 1670 Robert Boyle added iron to sulfuric acid. He showed the resulting (hydrogen) gas only burnt if air was present and that a fraction of the air (we would now call it oxygen) was consumed by the burning.(4) Hydrogen was first recognized as a distinct element in 1766 by Henry Cavendish, when he prepared it by reacting hydrochloric acid with zinc. He described hydrogen as "inflammable air from metals" and established that it was the same material (by its reactions and its density) regardless of which metal and which acid he used to produce it.(1) Cavendish also observed that when the substance was burned, it produced water. Lavoisier later named the element hydrogen (1783). The name comes from the Greek

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