C3

Transition Metals.

Transition metals are all typical metals, with the properties you would expect of a proper metal. They are good conductors of electricity and heat; dense; strong; shiny; less reactive than group 1 metals; do not react much with oxygen or water; higher melting points than group 1 metals.

Copper is hard, strong, and has a high melting point. It’s a good conductor of electricity and heat, and can be drawn out into wires and made into pipes. And as it’s below hydrogen in the reactivity series, it doesn’t react with water. These properties make it ideal for use in electrical wires and plumbing. Iron is another typical transition metal. Pure iron is malleable. But to make it confusing, pure iron and iron alloys have different qualities. Cast iron contains about 3%. It is brittle, and conducts heat well. Steels are alloys of iron with carbon. Low carbon steels have about 0.1% carbon. They are cheap, strong, and malleable. They are also used to make car bodies, ships, girders, nut and bolts. High carbon steels have up to 1.5% carbon. They are cheap, very hard, and ideal for drilling pieces.  Stainless steels contain chromium. Stainless steel does not rust or react much with acid. They are used to make cutlery, pots and pans, and containers for corrosive substances. Transition metals and their compounds make good catalysts. Iron is the catalyst used in the Haber process for making ammonia. Manganese oxide is a catalyst for the decomposition of hydrogen peroxide.  Nickel is useful for turning oil into fats for making margarine. Vanadium pentoxide is the catalyst used in the contact process for making sulphuric acid.

Transition metal compounds are often colourful due to the transition metal ion they contain. Potassium chromate is yellow. Potassium manganate is purple and copper sulphate is blue. The colours in gemstones, like blue sapphires and green emeralds, and the colours in pottery glazes are all due to transition metals. And weathered copper is a lovely green colour. Dyes and pigments are used to colour substances and they get their colours from transition metal compounds. And transition metal compounds are added to molten glass to make it coloured.

Alcohols

The general formula of an alcohol is Carbon n, hydrogen 2n+1, hydroxide. So an alcohol with 2 carbons has the formula C2H5OH. The first 5 alcohols are clear colourless liquids at room temperature. Alcohols are flammable and they burn to produce carbon dioxide and water. Methanol and ethanol evaporate easily and give off fumes e.g. they are volatile. This means they should be stored in closed containers away from heat sources. You would not want to accidently set fire to a cloud of alcohol vapour. The first 3 alcohols all mix completely with water. Alcohols react with oxygen to produce carboxylic acids and alcohols react with carboxylic acids to produce esters. All alcohols are toxic to some degree. Methanol is much more toxic than ethanol, and causes blindness. Ethanol damages the liver and brain. Alcohols,…