Beatty 17.4_ELECTROCHEM_(W4)_Simple Cells 2023_Answers.doc

1 Beatty Secondary School Science Department (Chemistry Unit) Chemistry 6092 Name: ___________________________________ ( ) Date: _______________ Class: 4E___ TOPIC: ELECTROCHEMISTRY (WORKSHEET 4) – ELECTRIC / SIMPLE CELLS Learning Objectives: (a) Describe the production of electrical energy from simple cells (i.e. two electrodes in an electrolyte) linked to the reactivity series and redox reactions (in terms of electron transfer). (b) Describe hydrogen, derived from water or hydrocarbons, as a potential fuel, reacting with oxygen to generate electricity directly in a fuel cell (details of the construction and operation of a fuel cell are not required). Multiple-Choice Questions 1 Apparatus was set up as shown. For which pair of metals would electrons flow in the direction shown? metal X metal Y A copper zinc B iron aluminium C iron magnesium D zinc silver ( D ) 2 The diagram below shows a ‘lemon cell’. Which of the following statements concerning this ‘lemon cell’ is not correct? A Electrons flow from the zinc rod to the copper rod. B The light bulb will also light up if the lemon is replaced by an orange. C The light bulb will not light up if the copper rod is replaced by a magnesium rod. D The electrolyte in a lemon cell is the organic acid and mineral salts in the lemon. ( C )

2 3 In an exp eriment, rods of copper and zinc are dipped into dilute sulfuric acid, with their top ends touching. Hydrogen b ubbles collect around the copper rod. Which statement about the experiment is correct? A Copper reacts with the acid. B Electrons flow from zinc to copper. C The zinc becomes coated with copper. D The zinc is less reactive than copper. ( B ) Structured Questions 4 The diagram represents a simple cell to produce electrical energy. One electrode is copper and the other one is aluminium, copper, iron, magnesium or zinc. (a) Suggest a suitable solution to be used as the electrolyte in this cell. copper(II) sulfate solution / dilute sulfuric acid (b) Give an ionic equation for the reaction taking place in this cell when zinc is used as the other electrode. Zn (s) + Cu2+ (aq) → Zn2+ (aq) + Cu (s) [for copper(II) sulfate] Zn (s) + 2H+ (aq) → Zn2+ (aq) + H2 (g) [for sulfuric acid] (c) Complete the table below by inserting the names of the metals, alu minium, copper, iron, magnesium and zinc. meter reading / V metal 2.72 magnesium 2.00 aluminium 1.10 zinc 0.78 iron 0.00 copper

3 5 The diagram shows a cell that can be used to make electrical energy. (a) Name the negative electrode in the cell. magnesium (b) Suggest a suitable substance which can be used as the solution. copper(II) sulfate solution / dilute sulfuric acid (c) Write an ionic equation for the reaction at the: (i) magnesium electrode, Mg (s)