C.5 Chemical Changes

Metal Oxide

• OILRIG • Reduction is gain of electrons • Fe2+ +2e- -> Fe

OIL RIG • Oxidation is loss of electrons • ca -> ca2+ +2e-

• When a substance is oxidised it gains oxygen • 2Mg + O2 -> 2MgO

• When a substance looses oxygen -Fe2O3+3CO -> 2Fe + 3CO2

A more reactive metal displaces a less reactive metal from a compound

• How easily it looses its outer shell electron

• Metal + Water -> Metal Hydroxide + Hydrogen • (Just split the water up) • 2K +2H2O -> 2KOH + H2 • The higher up the reactivity series the more vigorous the reaction

• Metal + Acid ->Salt + Hydrogen • Metals below hyrdogen do not react

Potassium Sodium Calcium Magnesium Aluminium (Carbon) Zinc Iron Tin Lead (Hydrogen) Copper Silver Gold Platinum Please, stop lovingly calling me a cute zebra instead try learning how cows scran grass period.

• As they have low reactivity • Do not react with oxygen

• If they are below Carbon in the reactivity series • Process called smelting • Metal Oxide + Carbon -> Metal + Carbon dioxide

a material containing enough metal to make it economical to extract

• Write out the equation with ions • Cross out spectator ions (those that don’t change)

• As high grade copper ores are becoming depleted • New methods which can extract metal from low - grade copper ore

• Bacteria is poured into the area • Bacteria can break down low grade ores • Produces an acidic solution called leachate • Either Electrolysis is used to obtain copper • Or displacement using scrap iron

• Cabbages are planted on low grade ore site • They take up copper in their roots • Once grown they are burned • Ash is dissolved in sulphuric acid to make solution containing copper compounds

Con - Very slow (can take years) - Some toxic chemicals may be released which harms wildlife Pro - Reduces need to obtain new ores by mining - Conserves limited supply of high grade ore

Con - Slow process Pro - Reduces need to obtain new ores by mining - Conserves limited supply of high grade ore

• Destruction of metal when it reacts with the atmosphere

• Rusting is the destruction of iron • In the presence of water and oxygen

• Own protective layer • Grease +oil • Paint • Electroplating (covering with a less reactive metal) • Sacrificial metal (covering with more reactive metal)

• Oxygen reacts with the top layer of aluminium • produces aluminium oxide • doesn’t flake away

• Place a block of more reactive metal on top (doesn’t have to fully cover the metal) • It will react first • The metal you are protecting is galvanised • for iron zinc is used • on ships mg is used