2 Reactions of metals with oxygen 31/03/2017When a metal reacts with oxygen it will form a METAL OXIDE. This is what happens when a metal rusts. We can make this reaction happen quicker by burning the metal.METAL + OXYGEN METAL OXIDECopy and complete the following reactions:Magnesium + oxygenCopper + oxygenCalcium + oxygenIron + oxygen
3 Reactions of metals with water 31/03/2017When a metal reacts with water hydrogen is always given off. The other product will be either a metal hydroxide or a metal oxide.METAL + WATER METAL OXIDE + HYDROGENMETAL + WATER METAL HYDROXIDE + HYDROGENCopy and complete the following reactions:Sodium + waterPotassium + waterCalcium + waterIron + steam
4 Reactions of metals with acids 31/03/2017When a metal reacts with an acid it gives off hydrogen (which can be “popped” using a lit splint). The other product is a salt.METAL + ACID SALT + HYDROGENe.g. magnesium + hydrochloric acid magnesium chloride + hydrogenCopy and complete the following reactions:Calcium + hydrochloric acidZinc + hydrochloric acidIron + hydrochloric acidLithium + sulphuric acid
6 An example question on reactivity 31/03/2017MetalReaction with dilute acidReaction with waterReaction with oxygenASome reactionSlow reactionBurns brightlyBNo reactionReacts slowlyCDViolent reactionEReasonable reactionReacts with steam only
7 Increasing reactivity The Reactivity Series31/03/2017Increasing reactivityPotassiumSodiumCalciumMagnesiumAluminiumCarbonZincIronLeadCopperSilverGoldThe Reactivity Series lists metals in order of reactivity:
8 Displacement reactions 31/03/2017A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound.MgMagnesiumSO4CuCopper sulphateThe magnesium DISPLACES the copper from copper sulphateSO4MgMagnesium sulphateCuCopper
9 Displacement reactions 31/03/2017A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound.For example, if you drop some magnesium into copper sulphate a reaction will happen because magnesium is more reactive than copper, so the reaction is:Magnesium + copper sulphate copper + magnesium sulphateHowever, if you drop some copper into magnesium sulphate NOTHING will happen.
10 Some example reactions… 31/03/2017ReactionPredictionObservationsZinc + copper sulphateZinc + lead nitrateCopper + lead nitrateCopper + silver nitrateExtension work – write down the equations for these reactions
11 Some example reactions… 31/03/2017ReactionPredictionObservationsZinc + copper sulphateReaction DID happenZinc + lead nitrateCopper + lead nitrateReaction DID NOT happenCopper + silver nitrateExtension work – write down the equations for these reactions
12 Extracting Metals Some definitions: 31/03/2017Some definitions:A METAL ORE is a mineral or mixture of minerals from which it is “economically practical” to extract some metal.Most ores contain METAL OXIDES (e.g. rust = iron oxide).To “extract” a metal from a metal oxide we need to REDUCE the oxygen. This is called a REDUCTION reaction.
13 Increasing reactivity How do we do it?31/03/2017PotassiumSodiumCalciumMagnesiumAluminiumCarbonZincIronTinLeadCopperSilverGoldPlatinumIncreasing reactivityMetals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSISMetals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACEThese LOW REACTIVITY metals blatantly won’t need to be extracted because they are SO unreactive you’ll find them on their own, not in a metal oxide
14 Extracting metals What is an ore? 31/03/2017What is an ore?In what form are metals usually found in the Earth?How do you get a metal out of a metal oxide?What is this type of reaction called?Type of metalExtraction processExamplesHigh reactivity (i.e anything above carbon)Middle reactivity (i.e. anything below carbon)Low reactivity
15 Iron oxide + carbon monoxide iron + carbon dioxide The Blast Furnace31/03/20171) HAEMATITE (iron ore), limestone and coke (carbon) are fed in here2) Hot air is blasted in here3) The carbon reacts with oxygen from the air to form carbon dioxide.4) The carbon dioxide reacts with more carbon to form carbon monoxide5) Carbon monoxide reduces iron oxide to iron. The molten iron is tapped off here6) Molten slag (waste) is tapped off hereIron oxide + carbon monoxide iron + carbon dioxide
16 Electrolysis Molecule of solid copper chloride 31/03/2017Molecule of solid copper chlorideMolecule of solid copper chloride after being dissolvedChloride ionCopper ion
17 Electrolysis Electrolysis is used to extract a HIGHLY REACTIVE metal. 31/03/2017Electrolysis is used to extract a HIGHLY REACTIVE metal.= chloride ion= copper ionWhen we electrolysed copper chloride the negative chloride ions moved to the positive electrode and the positive copper ions moved to the negative electrode – OPPOSITES ATTRACT!!!
18 These two processes are called REDOX REACTIONS 31/03/2017These happen during electrolysis:At the positive electrode the negative ions LOSE electrons to become neutral – this is OXIDATIONAt the negative electrode the positive ions GAIN electrons to become neutral – this is REDUCTIONThese two processes are called REDOX REACTIONSOILRIG – Oxidation Is Loss of electronsReduction Is Gain of electrons
19 Words – melting point, replaced, negative, bauxite, reactive, move 31/03/2017Purifying AluminiumAluminium has to be extracted from its ore (called ________) by electrolysis. This is because aluminium is very ___________. The ore is mixed with cryolite to lower its ________ ________. The ore is then melted so that the ions can ______. The positively charged aluminium ions gather at the ___________ electrode. Oxygen forms at the positive electrode and causes it to wear away, which means that they have to be __________ frequently.Words – melting point, replaced, negative, bauxite, reactive, move
20 Rusting Experiment NO RUST – no water NO RUST – no oxygen RUST 31/03/2017NO RUST – no waterNO RUST – no oxygenRUST
21 Rusting31/03/2017Rust is formed when iron reacts with water AND oxygen. It’s an example of an oxidation reaction which can be sped up using salt. There are several ways of dealing with rust:Regular painting or oilingGalvanising – this is when iron objects are coated with zincMaking objects out of a non-rusting metal, such as stainless steelAttaching zinc bars to ships – the water will react with the zinc before it reacts with the iron, because zinc is more reactive