1272020 Reactivity of Metals 1272020 Reactions of metals

12/7/2020 Reactivity of Metals

12/7/2020 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

12/7/2020 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. METAL + WATER METAL OXIDE + HYDROGEN METAL HYDROXIDE + HYDROGEN Copy and complete the following reactions: 1) Sodium + water 2) Potassium + water 3) Calcium + water 4) Iron + steam

12/7/2020 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. METAL + ACID e. g. magnesium + hydrochloric acid SALT + HYDROGEN magnesium chloride + hydrogen Copy and complete the following reactions: 1) Calcium + hydrochloric acid 2) Zinc + hydrochloric acid 3) Iron + hydrochloric acid 4) Lithium + sulphuric acid

12/7/2020 Complete the following reactions: 1) Lithium + water Lithium hydroxide + hydrogen 2) Lithium + hydrochloric acid Lithium chloride + hydrogen 3) Silver + oxygen Silver oxide 4) Magnesium + sulphuric acid Magnesium sulphate + hydrogen 5) Potassium + oxygen Potassium oxide 6) Aluminium + oxygen Aluminium oxide 7) Manganese + water Manganese oxide + hydrogen 8) Sodium + sulphuric acid Sodium sulphate + hydrogen 9) Lithium + oxygen Lithium oxide 10) Nickel + hydrochloric acid Nickel chloride + hydrogen

12/7/2020 An example question on reactivity Metal A B C D E Reaction with dilute acid Reaction with water Reaction with oxygen Some reaction Slow reaction Burns brightly No reaction Reacts slowly No reaction Violent reaction Slow reaction Burns brightly Reasonable reaction Reacts slowly Reacts with steam only

The Reactivity Series 12/7/2020 Potassium Sodium Calcium Magnesium The Reactivity Series lists metals in order of reactivity: Aluminium Carbon Zinc Iron Lead Copper Silver Gold

Displacement reactions 12/7/2020 A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound. Copper sulphate Magnesium Cu Mg The magnesium DISPLACES the copper from copper sulphate Mg SO 4 Magnesium sulphate Cu Copper SO 4

Displacement reactions 12/7/2020 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.

12/7/2020 Some example reactions… Reaction Prediction Observations Zinc + copper sulphate Zinc + lead nitrate Copper + silver nitrate Extension work – write down the equations for these reactions

12/7/2020 Some example reactions… Reaction Prediction Observations Zinc + copper sulphate Reaction DID happen Zinc + lead nitrate Reaction DID happen Copper + lead nitrate Reaction DID NOT happen Copper + silver nitrate Reaction DID happen Extension work – write down the equations for these reactions

Extracting Metals 12/7/2020 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.

How do we do it? 12/7/2020 Potassium Sodium Calcium Magnesium Metals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSIS Aluminium Carbon Zinc Iron Metals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACE Tin Lead Copper Silver Gold Platinum These 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

Extracting metals 12/7/2020 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 metal High reactivity (i. e anything above carbon) Middle reactivity (i. e. anything below carbon) Low reactivity Extraction process Examples

The Blast Furnace 12/7/2020 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 Iron oxide + carbon monoxide 5) Carbon monoxide reduces iron oxide to iron. The molten iron is tapped off here iron + carbon dioxide

Electrolysis 12/7/2020 Molecule of solid copper chloride after being dissolved Chloride ion Copper ion

Electrolysis 12/7/2020 Electrolysis is used to extract a HIGHLY REACTIVE metal. 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!!! = chloride ion = copper ion

Redox reactions 12/7/2020 These happen during electrolysis: 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 These two processes are called REDOX REACTIONS OILRIG – Oxidation Is Loss of electrons Reduction Is Gain of electrons

12/7/2020 Purifying 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

Rusting Experiment RUST NO RUST – no water 12/7/2020 NO RUST – no oxygen

Rusting 12/7/2020 Rust 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: 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