Presentation on theme: "29/05/2014 Reactivity of Metals. 29/05/2014 Reactions of metals with oxygen When a metal reacts with oxygen it will form a METAL OXIDE. This is what happens."— Presentation transcript:
29/05/2014 Reactions of metals with oxygen When 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 OXIDE Copy and complete the following reactions: 1)Magnesium + oxygen 2)Copper + oxygen 3)Calcium + oxygen 4)Iron + oxygen
29/05/2014 Reactions of metals with water When a metal reacts with water hydrogen is always given off. The other product will be either a metal hydroxide or a metal oxide. Copy and complete the following reactions: 1)Sodium + water 2)Potassium + water 3)Calcium + water 4)Iron + steam METAL + WATER METAL OXIDE + HYDROGEN METAL + WATERMETAL HYDROXIDE + HYDROGEN
29/05/2014 Reactions of metals with acids When a metal reacts with an acid it gives off hydrogen (which can be popped using a lit splint). The other product is a salt. Copy and complete the following reactions: 1)Calcium + hydrochloric acid 2)Zinc + hydrochloric acid 3)Iron + hydrochloric acid 4)Lithium + sulphuric acid METAL + ACID SALT + HYDROGEN e.g. magnesium + hydrochloric acid magnesium chloride + hydrogen
29/05/2014 An example question on reactivity MetalReaction with dilute acid Reaction with water Reaction with oxygen A Some reactionSlow reactionBurns brightly B No reaction Reacts slowly C No reaction D Violent reactionSlow reactionBurns brightly E Reasonable reaction Reacts with steam only Reacts slowly
29/05/2014 The Reactivity Series The Reactivity Series lists metals in order of reactivity: Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Lead Copper Silver Gold
29/05/2014 Displacement reactions Mg Magnesium SO 4 Cu Copper sulphate The magnesium DISPLACES the copper from copper sulphate SO 4 Mg Magnesium sulphate Cu Copper A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound.
29/05/2014 Displacement reactions A 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 sulphate However, if you drop some copper into magnesium sulphate NOTHING will happen.
29/05/2014 Some example reactions… ReactionPredictionObservations Zinc + copper sulphate Zinc + lead nitrate Copper + lead nitrate Copper + silver nitrate Extension work – write down the equations for these reactions
29/05/2014 Some example reactions… ReactionPredictionObservations Zinc + copper sulphateReaction DID happen Zinc + lead nitrateReaction DID happen Copper + lead nitrateReaction DID NOT happen Copper + silver nitrateReaction DID happen Extension work – write down the equations for these reactions
29/05/2014 Extracting Metals Some 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.
29/05/2014 How do we do it? Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Copper Silver Gold Platinum Metals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSIS Metals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACE These LOW REACTIVITY metals blatantly wont need to be extracted because they are SO unreactive youll find them on their own, not in a metal oxide
29/05/2014 Extracting metals 1)What is an ore? 2)In what form are metals usually found in the Earth? 3)How do you get a metal out of a metal oxide? 4)What is this type of reaction called? Type of metalExtraction processExamples High reactivity (i.e anything above carbon) Middle reactivity (i.e. anything below carbon) Low reactivity
29/05/2014 The Blast Furnace 1) HAEMATITE (iron ore), limestone and coke (carbon) are fed in here 2) Hot air is blasted in here 3) The carbon reacts with oxygen from the air to form carbon dioxide. 4) The carbon dioxide reacts with more carbon to form carbon monoxide 6) Molten slag (waste) is tapped off here 5) Carbon monoxide reduces iron oxide to iron. The molten iron is tapped off here Iron oxide + carbon monoxideiron + carbon dioxide
29/05/2014Electrolysis Molecule of solid copper chloride Molecule of solid copper chloride after being dissolved Chloride ion Copper ion
29/05/2014Electrolysis Electrolysis is used to extract a HIGHLY REACTIVE metal. = chloride ion = copper ion When 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!!!
29/05/2014 Redox reactions These happen during electrolysis: These two processes are called REDOX REACTIONS OILRIG – Oxidation Is Loss of electrons Reduction Is Gain of electrons At the positive electrode the negative ions LOSE electrons to become neutral – this is OXIDATION At the negative electrode the positive ions GAIN electrons to become neutral – this is REDUCTION
29/05/2014 Purifying Aluminium Aluminium 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
29/05/2014 Rusting Experiment RUST NO RUST – no water NO RUST – no oxygen
29/05/2014Rusting Rust is formed when iron reacts with water AND oxygen. Its an example of an oxidation reaction which can be sped up using salt. There are several ways of dealing with rust: 1)Regular painting or oiling 2)Galvanising – this is when iron objects are coated with zinc 3)Making objects out of a non-rusting metal, such as stainless steel 4)Attaching zinc bars to ships – the water will react with the zinc before it reacts with the iron, because zinc is more reactive