oxygen to produce metal oxides. Use these to identify where reduction and oxidation has taken place. 5.4.1.2 When metals with other substances the metal atoms form positive ions. The reactivity of a metal is related to its tendency to form positive ions. Metals can be arranged in order of their reactivity in a reactivity series. The metals potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper can be put in order of their reactivity from their reactions with water and dilute acids. The non-metals hydrogen and carbon are often included in the reactivity series. A more reactive metal can displace a less reactive metal from a compound. The reactions of metals with water and acids are limited to room temperature and do not include reactions with steam. Recall and describe the reactions, if any, of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with water or dilute acids, where appropriate, to place these metals in order of reactivity. Explain how the reactivity of metals with water or dilute acids is related to the tendency of the metal to form its positive ion. 1 Draw the atomic structure of metals and the ion formed. Use these to describe how the ion has been formed. Make links between the ability to form ions and the reactivity with water and acid. Grade 9: explain the trends in reactivity of Group 1 in terms of atomic structure. Describe what occurs in a displacement reaction, using suitable examples. Explain why displacement occurs. Compare the year of discovery of a metallic element with its position in the reactivity series. Demo, and where appropriate practically investigate, the reactivity of some of the metals with water and acid. Use YouTube clips or let students investigate the reactivity of the remaining combinations. Use findings to construct a reactivity series. Compare this to the actual reactivity series. AT 6. Mixing of reagents to explore chemical changes and/or products. Video clips: YouTube:
Deduce an order of reactivity of metals based on experimental results. Link discoveries to new technology such as the invention of the battery. 5.4.1.3 Unreactive metals such as gold are found in the Earth as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal. Metals less reactive than carbon can be extracted from their oxides by reduction with carbon. Reduction involves the loss of oxygen. Knowledge and understanding are limited to the reduction of oxides using carbon. Knowledge of the details of processes used in the extraction of metals is not required. Interpret or evaluate specific metal extraction processes when given appropriate information. Identify the substances which are oxidised or reduced in terms of gain or loss of oxygen. WS 1.4, 4.1 1 Describe how carbon is used to reduce metal oxides. Explain how this takes place in terms of movement of electrons. Identify which products have been oxidised in extraction examples. Explain how this takes place in terms of movement of electrons. Reduce iron oxide using carbon: Research different methods for extraction metals from their oxides. Compare and contrast the methods, evaluating the methods in terms of environmental, economic and social impacts. Video clip YouTube: 5.4.1.4 (HT only) Oxidation is the loss of electrons and reduction is the gain of electrons. Write ionic equations for displacement reactions. Identify in a reaction, symbol equation or half equation which species 1 balanced symbol equations/half equations for the displacement of metal oxides. Use these to identify which species has been oxidised or reduced. Carry out simple displacement reactions. For these write ionic equations. Video clips YouTube:
are oxidised and which are reduced. WS 4.1 MS 3a Give reasons for your answers. 5.4.2 Reactions of acids Spec ref. Summary of the specification content Learning outcomes What most candidates should be able to do Suggested timing (hours) Opportunities to develop Scientific Communication skills Opportunities to develop and apply practical and enquiry skills Self/peer assessment opportunities and resources Reference to past questions that indicate success 5.4.2.1 Acids react with some metals to produce salts and hydrogen. Knowledge of reactions limited to those of magnesium, zinc and iron with hydrochloric and sulfuric acids. (HT only) Explain in terms of gain or loss of electrons, that these are redox reactions. 1 Investigate the reactions of the following metals with sulfuric acid: magnesium zinc iron. word and balanced symbol equations for these reactions.
As the pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10. MS 2h Describe neutrality in terms on hydrogen ion concentration. Describe relative acidity in terms of hydrogen ion concentration. AT 8 5.4.3 Electrolysis Spec ref. Summary of the specification content Learning outcomes What most candidates should be able to do Suggested timing (hours) Opportunities to develop Scientific Communication skills Opportunities to develop and apply practical and enquiry skills Self/peer assessment opportunities and resources Reference to past questions that indicate success 5.4.3.1 When an compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes. Passing an electric current through electrolytes causes the ions to move to the (HT only) Throughout 5.4.3: Higher Tier students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations. WS 4.1 1 Explain why solid ionic compounds cannot conduct electricity but ionic compounds can conduct electricity when melted or dissolved in water. Define the term electrolyte. Describe how an electric current can pass through an ionic compound. Carry out the electrolysis of solutions following the RSC method: Write balanced symbol equations for these reactions. Write half equations for the reactions that occur at each electrode. Video clips: YouTube:
electrodes. Positively charged ions move to the negative electrode (the cathode), and negatively charged ions move to the positive electrode (the anode). Ions are discharged at the electrodes producing elements. This process is called electrolysis. Explain what happens to positive and negative ions during electrolysis and how elements form from ions. 5.4.3.2 When a simple ionic compound (eg lead bromide) is electrolysed in the molten state using inert electrodes, the metal (lead) is produced at the cathode and the (bromine) is produced at the anode. Students should be able to predict the products of the electrolysis of binary ionic compounds in the molten state. 0.5 Calculate the atom economy for simple examples. Extended writing: write instructions to another student how to calculate the atom economy giving explained examples. Demo the electrolysis of lead bromide. A safer alternative for practical work is anhydrous zinc chloride. Write balanced half equations for the reactions that occur at both electrodes. Video clip: YouTube: 5.4.3.3 Metals can be extracted from molten compounds using electrolysis. Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon. Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current. Explain why a mixture is used as the electrolyte. Explain why the positive electrode must be continually replaced. WS 1.4, 4.1 1 Recall the reactivity series. Give reasons why some metals have to be extracted by electrolysis. Extended writing: describe how aluminium is extracted from its ore. Write balanced half equations for the reactions Research how aluminium is extracted from its ore. Write balanced half equations for the reactions that occur at both electrodes.
Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode). that occur at both electrodes. Extended writing: describe how reactive elements were discovered by electrolysis. Construct a timeline. 5.4.3.4 The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved. At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen. At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced. This happens because in the aqueous solution water molecules break down producing hydrogen ions and Be able to predict the products of the electrolysis of aqueous solutions containing a single ionic compound. WS 2.1, 2.2, 2.3, 2.4, 2.6 2 Define the term aqueous. Extended writing: describe how an aqueous solution is electrolysed. Explain why the following atoms could be produced: hydrogen oxygen. Required practical 9: Investigate what happens when aqueous solutions are electrolysed using inert electrodes. This should be an investigation involving developing a hypothesis. AT skills covered by this practical activity: 3, 7 and 8.