Chem4 Flashcards
Whst is a thermite reaction
A single displacement reaction of an oxide with a powder of an elemental metal like aluminum. Both reactants are in powdered form to increase their surface area and reactivity. Solid state thermite reactions diminishes deformation of products which reduces need for additional shaping. Magnesium is mined from seawater with calcium carbonate, provided by clams, that decomposes into calcium oxide and carbon dioxide. The calcium oxide combines in a synthesis reaction with water to make calcium hydroxide. Calcium hydroxide is then reacted with magnesium which displaces the calcium to make magnesium hydroxide. The magnesium hydroxide is then reacted with hydrochloric acid in a double displacement reaction that makes magnesium chloride which then decomposes to make elemental magnesium. A neutralization step avoids release of pollutants. Instead of releasing sulphur dioxide its converted to sulphuric acid. Sources of sulphur dioxide waste are metal purification. Magnesium aluminum alloys are lighter and more resistant to corrosion than pure aluminum. Copper smelting includes smelting, slag cleaning, converting and anode furnaces, at different heights to increase oxygen supply. Slag cleaning is the only physical process because its where products separate due to differences in density. Slag is a byproduct of chemical reactions. Two major uses of copper are electrical wiring and plumbing. Gold is found solid in nature, but its usually mixed with rock so it must be liquefied then reconverted to solid form. Gold is displaced by zinc, and the cyanide solution is recycled to save resources.
