Reactivity with metals
- 2. 07/03/12 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: • Magnesium + oxygen • Copper + oxygen • Calcium + oxygen • Iron + oxygen
- 3. 07/03/12 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 + WATER METAL HYDROXIDE + HYDROGEN Copy and complete the following reactions: • Sodium + water • Potassium + water • Calcium + water • Iron + steam
- 4. 07/03/12 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 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
- 5. 07/03/12 Complete the following reactions: • Lithium + water Lithium hydroxide + hydrogen • Lithium + hydrochloric acid Lithium chloride + hydrogen • Silver + oxygen Silver oxide • Magnesium + sulphuric acid Magnesium sulphate + hydrogen • Potassium + oxygen Potassium oxide • Aluminium + oxygen Aluminium oxide • Manganese + water Manganese oxide + hydrogen • Sodium + sulphuric acid Sodium sulphate + hydrogen • Lithium + oxygen Lithium oxide • Nickel + hydrochloric acid Nickel chloride + hydrogen
- 6. 07/03/12 An example question on reactivity Metal Reaction with Reaction Reaction dilute acid with water with oxygen Some reaction Slow reaction Burns brightly A No reaction No reaction Reacts slowly B No reaction No reaction No reaction C Violent reaction Slow reaction Burns brightly D Reasonable Reacts with Reacts slowly E reaction steam only
- 7. 07/03/12 The Reactivity Series Potassium Sodium Calcium Magnesium The Reactivity Series lists Aluminium metals in order of reactivity: Carbon Zinc Iron Lead Copper Silver Gold
- 8. Displacement reactions 07/03/12 A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound. Magnesium Copper sulphate Mg Cu SO4 The magnesium DISPLACES the copper from copper sulphate Mg SO4 Cu Magnesium sulphate Copper
- 9. 07/03/12 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.
- 10. 07/03/12 Some example reactions… Reaction Prediction Observations Zinc + copper sulphate Zinc + lead nitrate Copper + lead nitrate Copper + silver nitrate Extension work – write down the equations for these reactions
- 11. 07/03/12 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
- 12. 07/03/12 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.
- 13. How do we do it? 07/03/12 Potassium Sodium Metals ABOVE CARBON, because Calcium of their high reactivity, are Magnesium extracted by ELECTROLYSIS Aluminium Carbon Metals BELOW CARBON are Zinc extracted by heating them with Iron carbon in a BLAST FURNACE Tin Lead Copper These LOW REACTIVITY metals blatantly won’t need to be extracted Silver because they are SO unreactive you’ll Gold find them on their own, not in a metal Platinum oxide
- 14. 07/03/12 Extracting metals • 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
- 15. 07/03/12 The Blast Furnace 1) HAEMATITE (iron ore), limestone and coke (carbon) are fed in here 2) Hot air is 3) The carbon reacts with blasted in oxygen from the air to form here carbon dioxide. 4) The carbon dioxide reacts with more carbon to form carbon monoxide 6) Molten slag 5) Carbon monoxide reduces (waste) is iron oxide to iron. The tapped off here molten iron is tapped off here Iron oxide + carbon monoxide iron + carbon dioxide
- 16. 07/03/12 Electrolysis Molecule of solid copper chloride Molecule of solid copper chloride after being dissolved Chloride Copper ion ion
- 17. 07/03/12 Electrolysis 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
- 18. Redox reactions 07/03/12 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
- 19. 07/03/12 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
- 20. 07/03/12 Rusting Experiment RUST NO RUST – NO RUST – no water no oxygen
- 21. Rusting 07/03/12 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