Chemical changes

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Sample objectives

What this unit covers

• Reactivity of metals: Explain that some metal oxides dissolve in water to form alkaline solutions.
• Reactivity of metals: Describe non-metal oxides as acidic.
• Reactivity of metals: Use displacement reaction results to compare metal reactivity.
• Reactivity of metals: Describe how metals can be arranged in order of reactivity.
• Reactivity of metals: Explain that most metals are found as compounds that require chemical reactions for extraction.
• Reactivity of metals: Describe reduction of a metal oxide by carbon in terms of oxygen removal.
• Reactivity of metals: (HT only) Write simple ionic half equations for oxidation and reduction when ions and charges are supplied.
• Reactivity of metals: (HT only) Define reduction as gain of electrons.
• Reactions of acids: Explain why less reactive metals may not react readily with dilute acids.
• Reactions of acids: Predict the salt produced when nitric acid reacts with a metal.
• Reactions of acids: Describe the test for carbon dioxide using limewater.
• Reactions of acids: Describe neutralisation as the reaction between an acid and a base or alkali.
• Reactions of acids: Identify suitable apparatus for preparing, filtering and crystallising a soluble salt. (AT 2, AT 3, AT 4, AT 6)
• Reactions of acids: Describe safety precautions when using acids and heating solutions during salt preparation.
• Reactions of acids: Explain why pH decreases when an alkali is neutralised by an acid.
• Reactions of acids: Use pH data to identify whether a solution is acidic, neutral or alkaline.
• Reactions of acids: (HT only) Compare pH changes when strong and weak acids are diluted.
• Reactions of acids: (HT only) Describe a strong acid as completely ionised in aqueous solution.
• Electrolysis: Identify the negative electrode as the cathode.
• Electrolysis: Describe an electrolyte as a liquid that contains free-moving ions.
• Electrolysis: Predict that a metal forms at the cathode when a molten ionic compound is electrolysed.
• Electrolysis: Predict that a non-metal forms at the anode when a molten ionic compound is electrolysed.
• Electrolysis: Describe oxide ions losing electrons at the anode to form oxygen.
• Electrolysis: Explain why aluminium oxide is dissolved in molten cryolite during extraction.
• Electrolysis: Predict that hydrogen is produced at the cathode if the metal is more reactive than hydrogen.
• Electrolysis: Predict that chlorine, bromine or iodine is produced at the anode when the corresponding halide ion is present.
• Electrolysis: (HT only) Link half equations to observed products in molten and aqueous electrolysis.
• Electrolysis: (HT only) Balance charge and atoms in simple electrolysis half equations.