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4. Chemical changes

Reactivity of metals

4 lessons
4.1 Oxidation and reduction Oxidation as gain of oxygen and reduction as loss of oxygen, metals reacting with oxygen to form oxides, and identifying which substance is oxidised and which is reduced in a redox reaction. AQA Edexcel OCR 4.2 The reactivity series and displacement The order of reactivity of metals including carbon and hydrogen, how metals react with water and dilute acids, displacement reactions, and how reactivity relates to the tendency of a metal to form positive ions. AQA Edexcel OCR 4.3 Extracting metals with carbon Why unreactive metals are found as elements, how metals less reactive than carbon are extracted by reduction with carbon, why more reactive metals are extracted by electrolysis, and how cost affects the method used. AQA Edexcel OCR 4.4 Oxidation and reduction in terms of electrons Oxidation as loss of electrons and reduction as gain of electrons (OIL RIG), writing ionic equations and half equations for displacement reactions, spectator ions, and identifying what is oxidised and reduced. Higher only AQA Edexcel OCR

Reactions of acids

7 lessons
4.5 Acids, alkalis and the pH scale What makes a solution acidic or alkaline, the pH scale from 0 to 14, measuring pH with universal indicator or a pH probe, and the colours of common indicators. AQA Edexcel OCR 4.6 Neutralisation and the reactions of acids How acids react with metals, metal oxides, metal hydroxides and metal carbonates, naming and writing formulae for salts, the ionic equation for neutralisation, and the tests for hydrogen and carbon dioxide. AQA Edexcel OCR 4.7 Required practical: making a soluble salt How to make pure, dry crystals of a soluble salt such as copper sulfate from an insoluble base and an acid: warming the acid, adding excess base, filtering, evaporating and crystallising, and why each step is done. AQA Edexcel OCR 4.8 Core practical: pH change in neutralisation Edexcel core practical: adding calcium hydroxide a little at a time to dilute hydrochloric acid, measuring the pH after each addition, and plotting and explaining the pH curve. Edexcel 4.9 Strong and weak acids The difference between strong and weak acids (full or partial ionisation), the difference between concentrated and dilute, and how pH changes by one unit for each factor of 10 change in hydrogen ion concentration. Higher only AQA Edexcel OCR 4.10 Solubility rules and preparing salts The general rules for which common salts are soluble in water, predicting precipitates, and the methods for preparing a soluble salt by titration and an insoluble salt by precipitation. Edexcel 4.11 Titrations How to carry out an accurate acid-alkali titration using a pipette, burette and indicator, how to read a burette, and how to identify concordant titres and calculate a mean titre. AQA Edexcel OCR

Electrolysis

6 lessons
4.12 Electrolysis of molten ionic compounds What electrolysis is, why an ionic compound must be molten or dissolved, how positive ions move to the cathode and negative ions to the anode, and how to predict the products of electrolysing a molten binary ionic compound. AQA Edexcel OCR 4.13 Extracting aluminium by electrolysis Why aluminium is extracted by electrolysis, why the aluminium oxide is dissolved in molten cryolite, the reactions at each electrode, why the carbon anodes must be replaced, and why the process is expensive. AQA Edexcel OCR 4.14 Electrolysis of aqueous solutions How water provides hydrogen and hydroxide ions in solution, the rules for predicting the products at each electrode when solutions are electrolysed, and examples including sodium chloride and copper sulfate solutions. AQA Edexcel OCR 4.15 Half equations at the electrodes Writing and balancing half equations for the reactions at the cathode and anode during electrolysis, and explaining that reduction happens at the cathode and oxidation at the anode. Higher only AQA Edexcel OCR 4.16 Required practical: electrolysis of aqueous solutions How to electrolyse aqueous solutions with inert electrodes, collect and test the gases produced, record observations at each electrode and test a hypothesis about the products. AQA OCR 4.17 Core practical: electrolysis of copper sulfate Electrolysing copper sulfate solution with inert and then copper electrodes, measuring the change in mass of each copper electrode at different currents, and how the same process is used to purify copper. Edexcel OCR