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1 of 22© Boardworks Ltd 2011 Extracting Metals by Electrolysis
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3 of 22© Boardworks Ltd 2011 Extracting metals from ores Most metals that we use are found combined with other elements, as compounds in ores. These metals must be extracted from their ores before they can be made useful. The method of extraction which is most appropriate depends on the reactivity of the metal being extracted. This can be discovered using the reactivity series. Metals above carbon in the reactivity series must be extracted using electrolysis. increasing reactivity potassium sodium calcium magnesium aluminium zinc iron copper gold lead silver (carbon) (hydrogen) platinum
4 of 22© Boardworks Ltd 2011 What is electrolysis? Electrolysis is a process that uses electricity to separate the elements in a compound. Electrolysis is expensive and so it is only used to extract reactive metals that cannot be extracted in other ways. Aluminium is a reactive metal that is found in the ore bauxite combined with oxygen as aluminium oxide (Al 2 O 3 ). Electrolysis breaks down the Al 2 O 3 into aluminium and oxygen. As the aluminium loses oxygen, reduction takes place. What is the word equation for the extraction of aluminium? aluminium oxide aluminium oxygen +
5 of 22© Boardworks Ltd 2011 Ionic substances Electrolysis involves breaking down ionic substances into simpler substances using electricity. An ionic substance contains charged particles called ions. An ion is an atom that has gained or lost electrons and so carries a positive or negative charge, which is shown after its formula. In electrolysis, the ionic substance must be dissolved in water or melted so that the ions are free to move. Ions with a positive charge have lost electrons, and ions with a negative charge have gained electrons. Al 3+ Al Aluminium atom Aluminium ion loses 3 electrons
6 of 22© Boardworks Ltd 2011 Oxidation and reduction heat In electrolysis, the substance that the current passes through and splits up is called the electrolyte. Positive ions move to the negative electrode and gain electrons. This is reduction. Negative ions move to the positive electrode and lose electrons. This is oxidation. The electrolyte contains positive and negative ions. What happens to these ions during electrolysis?
7 of 22© Boardworks Ltd 2011 OILRIG An easy way to remember what happens to the electrons during oxidation and reduction is to think OILRIG. Equations written to show what happens to electrons during oxidation and reduction are called half-equations, i.e.: Oxidation Is Loss of electrons Reduction Is Gain of electrons magnesium + oxygen magnesium oxide 2Mg (s) O 2 (g) 2MgO (s) + oxidation: Mg Mg e - reduction: O 2 + 4e - 2O 2-
8 of 22© Boardworks Ltd 2011 Extracting aluminium Aluminium is one of the most useful metals in the world. Aluminium ore (bauxite) is more reactive than carbon and has a very high melting point (2050 °C). Electrolysis is used to extract aluminium from its ore. Why is it not possible to extract aluminium by heating its ore with carbon? In electrolysis, the ore is dissolved in a compound called cryolite (Na 3 AlF 6 ), which effectively lowers the melting point to 1,000 °C.
9 of 22© Boardworks Ltd 2011 Aluminium from bauxite
10 of 22© Boardworks Ltd 2011 Redox equations – aluminium What processes occur at the electrodes during the electrolysis of aluminium oxide (Al 2 O 3 )? What is the overall equation for this extraction by electrolysis? At the negative electrode: Al e - Al (reduction) At the positive electrode: 2O 2- O 2 + 4e - (oxidation) aluminium oxide aluminium + oxygen 2 Al 2 O 3 (l) 4 Al (l) + 3 O 2 (g)
11 of 22© Boardworks Ltd 2011 Economics of electrolysis The extraction of aluminium from its ore by electrolysis requires large amounts of energy in the form of expensive electricity to complete the many stages in the process. To reduce costs, aluminium extraction plants are often located near sources of cheap electricity such as hydroelectric dams. This energy is needed both to melt the aluminium oxide and to split up the compound.
12 of 22© Boardworks Ltd 2011 Extracting aluminium summary
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14 of 22© Boardworks Ltd 2011 How is copper purified? Copper can occur as a native metal, but more often it is found combined with other elements, such as in the ore malachite. Copper is an excellent conductor and does not corrode quickly which makes it a good material for wiring and plumbing. Only pure copper can be used for electric wires because even very low levels of impurities will reduce the conductivity. The copper extracted from compounds by reduction with carbon is impure. Electrolysis can be used after reduction to remove the impurities and obtain pure copper.
15 of 22© Boardworks Ltd 2011 Purifying copper using electrolysis
16 of 22© Boardworks Ltd 2011 Labelling copper purification
17 of 22© Boardworks Ltd 2011 Redox equations – copper What happens at the electrodes during the purification of copper by electrolysis? At the negative electrode: Cu e - Cu (reduction) This process is carried out on a huge scale in industry. The copper formed on the negative electrodes is 99.99% pure. At the positive electrode: Cu Cu e - (oxidation) The precious metals recovered from the impurities are also sold off and help to make this industrial process profitable.
18 of 22© Boardworks Ltd 2011 Purifying copper – true or false?
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20 of 22© Boardworks Ltd 2011 Glossary
21 of 22© Boardworks Ltd 2011 Anagrams
22 of 22© Boardworks Ltd 2011 Multiple-choice quiz
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ELECTROLYSIS. What is a redox reaction? Oxidation is the addition of oxygen to a substance and reduction is the removal of oxygen from a substance. lead.
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Extracting metals. Methods of extracting metals The Earth's crust contains metals and metal compounds such as gold, iron oxide and aluminium oxide, but.
ELECTROLYSIS Noadswood Science, Electrolysis Tuesday, February 02, 2016 To understand electrolysis and products it makes.
1 of 6© Boardworks Ltd 2014 Electrolysis. 2 of 6© Boardworks Ltd 2014 What are ionic compounds? Ionic compounds are made up of positive ions and negative.
Electrolysis L.O: To be able to describe the uses and predict the products of electrolysis.
ELECTROLYSIS Module C2 Splitting up ionic compounds (F) Molten compounds Ionic solutions & discharge rules Q = It and OILRIG Brine and purifying copper.
3.17 Uses of electrolysis Purification of copper: Impure copper extracted from its ore by heating the ore with carbon (smelting) – a mixture of copper.
© Boardworks Ltd of of 11© Boardworks Ltd 2006 Are some metals easier to find than others? Finding metals.
1 of 10© Boardworks Ltd 2013 Redox Reactions and Rusting To enable the animations and activities in this presentation, Flash Player needs to be installed.
One plus, two plus, three plus, NO Three minus, two minus, one minus, NO.
1 of 28© Boardworks Ltd 2011 Smart Teach Chemistry Section 4 Extraction of metals.
© Boardworks Ltd of 38 KS4 Chemistry Useful Metals.
Chemicals of the Natural Environment. C5 Lesson 8.
ELECTROLYSIS EXPLAIN THE PROCESS OF ELECTROLYSIS AND ITS USES.
Chemical effect of electric current How things work.
Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Copper Silver Gold More reactive 1.Complete the word equation: Copper oxide + sodium
MODULE C5: CHEMICALS OF THE NATURAL ENVIRONMENT. Atmosphere Molecular elements (e.g. oxygen, nitrogen, ozone) and compounds (e.g.carbon dioxide, water)
12.6 – How can we use ions in solutions? Ionic compounds have many uses and can provide other substances. Electrolysis is used to produce alkalis and elements.
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.
Learning objective: demonstrate electrolysis as the decomposition of a molten salt by an electric current see patterns in the changes at the electrodes.
Starter 1. The following metals were reacted with water. Put them in order of reactivity, with the least reactive metal first. Lithium, potassium, calcium,
What is an ion? What is copper sulphate? What is copper?What is sulphate? When an atom loses or gains one or more electrons it becomes an ion. An ion either.
METALS. Introducing metal extraction 1.First, substances other than the metal compound are removed (concentration). 2.Next, the metal itself is extracted.
The Extraction Of Metals Ashvini Jagassar- 5C Chemistry. Mr. Dookoo.
Revision lesson. Metals found in the ground are normally found as a METAL ORE – combined with other elements in compounds Metals found on their own.
Metals, Making Electricity and Corrosion. Metals The job that a metal is used for is determined by its physical and chemical properties. Physical properties.
© Boardworks Ltd 2003 KS4: Useful Materials From Metal Ores.
Electrolysis breaks down ionic substances into simpler substances by using electricity!
Metals. Learning Objectives Use reactivity data to determine a reactivity series Relate extraction method to reactivity of metals Write word/symbol equations.
Extracting metals. Why extract metals? Most metals are found in the Earth’s crust combined with other elements in rocks known as ores. For example, iron.
Metals. Elements found in the Earth’s crust Oxygen Silicon Aluminium Iron Calcium Sodium Magnesium Potassium Titanium Hydrogen All other elements 46%
C5 Revision. So what’s in air? Oxygen. Nitrogen. Carbon dioxide. Water. Argon. What about dry air? The same apart from water.
D. Crowley, 2007 Metal & Reactivity. Thursday, September 17, 2015 To link the uses of a metal to its reactivity.
Electrolysis project Electrode: Is an electrical conductor that is used to pass current through an electrolyte.
Conductors and non-conductors Conductors are materials that conduct electricity. Non-conductors or insulators are materials that do not conduct electricity.
Chapter 17. Which metals were discovered earliest? Gold, copper, silver = less reactive metals Found “native” ie. as pure metal More reactive.
Chapter 22 REDOX. The Meaning of Oxidation and Reduction Oxidation Numbers Balancing Redox Equations.
Making aluminium. Keywords and big picture starter Bauxite, Aluminium oxide, graphite, cryolite, electricity, molten, malleable, strong, low density and.
Chemistry C Atomic Structure The element Lithium has a symbol of Li. 3 electrons (atomic number) and an atomic mass of 7 Atoms are made of protons,
1 of 50© Boardworks Ltd 2007 Lesson 1- Introduction to Redox Reactions Define oxidation and reduction in terms of oxygen loss/gain Define redox in terms.
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Write down the Reactivity Series from Potassium to Gold. Potassium Sodium Lithium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Hydrogen Copper.
Metal ores and mining Ores are naturally occurring rocks found in the Earth’s crust. They contain metal/metal compounds in sufficient amounts to make it.
Topic 3 Metals and their uses. Extracting metals Metals are found in the Earth’s crust They are often chemically combined with other elements – this is.
Title: Lesson 6 Electrolytic Cells Learning Objectives: – Describe electrolytic cells – Identify at which electrode oxidation and reduction takes place.
AQA Science © Nelson Thornes Ltd C2 6 Summary Electrolysis Decide on the answer(s) then click and a rectangle will surround the correct answer(s).
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