31/03/2017 Reactivity of Metals

Reactions of metals with oxygen 31/03/2017 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: Magnesium + oxygen Copper + oxygen Calcium + oxygen Iron + oxygen

Reactions of metals with water 31/03/2017 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 + WATER METAL HYDROXIDE + HYDROGEN Copy and complete the following reactions: Sodium + water Potassium + water Calcium + water Iron + steam

Reactions of metals with acids 31/03/2017 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 SALT + HYDROGEN e.g. magnesium + hydrochloric acid magnesium chloride + hydrogen Copy and complete the following reactions: Calcium + hydrochloric acid Zinc + hydrochloric acid Iron + hydrochloric acid Lithium + sulphuric acid

Complete the following reactions: 31/03/2017 Lithium + water Lithium + hydrochloric acid Silver + oxygen Magnesium + sulphuric acid Potassium + oxygen Aluminium + oxygen Manganese + water Sodium + sulphuric acid Lithium + oxygen Nickel + hydrochloric acid Lithium hydroxide + hydrogen Lithium chloride + hydrogen Silver oxide Magnesium sulphate + hydrogen Potassium oxide Aluminium oxide Manganese oxide + hydrogen Sodium sulphate + hydrogen Lithium oxide Nickel chloride + hydrogen

An example question on reactivity 31/03/2017 Metal Reaction with dilute acid Reaction with water Reaction with oxygen A Some reaction Slow reaction Burns brightly B No reaction Reacts slowly C D Violent reaction E Reasonable reaction Reacts with steam only

Increasing reactivity The Reactivity Series 31/03/2017 Increasing reactivity Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Lead Copper Silver Gold The Reactivity Series lists metals in order of reactivity:

Displacement reactions 31/03/2017 A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound. Mg Magnesium SO4 Cu Copper sulphate The magnesium DISPLACES the copper from copper sulphate SO4 Mg Magnesium sulphate Cu Copper

Displacement reactions 31/03/2017 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.

Some example reactions… 31/03/2017 Reaction Prediction Observations Zinc + copper sulphate Zinc + lead nitrate Copper + lead nitrate Copper + silver nitrate Extension work – write down the equations for these reactions

Some example reactions… 31/03/2017 Reaction Prediction Observations Zinc + copper sulphate Reaction DID happen Zinc + lead nitrate Copper + lead nitrate Reaction DID NOT happen Copper + silver nitrate Extension work – write down the equations for these reactions

Extracting Metals Some definitions: 31/03/2017 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.

Increasing reactivity How do we do it? 31/03/2017 Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Copper Silver Gold Platinum Increasing reactivity 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 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 What is an ore? 31/03/2017 What 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 metal Extraction process Examples High reactivity (i.e anything above carbon) Middle reactivity (i.e. anything below carbon) Low reactivity

Iron oxide + carbon monoxide iron + carbon dioxide The Blast Furnace 31/03/2017 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 5) Carbon monoxide reduces iron oxide to iron. The molten iron is tapped off here 6) Molten slag (waste) is tapped off here Iron oxide + carbon monoxide iron + carbon dioxide

Electrolysis Molecule of solid copper chloride 31/03/2017 Molecule of solid copper chloride Molecule of solid copper chloride after being dissolved Chloride ion Copper ion

Electrolysis Electrolysis is used to extract a HIGHLY REACTIVE metal. 31/03/2017 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!!!

These two processes are called REDOX REACTIONS 31/03/2017 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

Words – melting point, replaced, negative, bauxite, reactive, move 31/03/2017 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

Rusting Experiment NO RUST – no water NO RUST – no oxygen RUST 31/03/2017 NO RUST – no water NO RUST – no oxygen RUST

Rusting 31/03/2017 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: Regular painting or oiling Galvanising – this is when iron objects are coated with zinc Making objects out of a non-rusting metal, such as stainless steel Attaching zinc bars to ships – the water will react with the zinc before it reacts with the iron, because zinc is more reactive