Electrochemical reactions: Grade 12 Past Paper Questions

An electrolytic cell is set up for the electrolysis of a concentrated copper(II) chloride solution, CuCl₂(conc.). X and Y are carbon electrodes. 9.1 Define the term electrolysis. 9.2 Write down balanced equations for TWO reactions that will take place at the anode. 9.3 Write down the NAME or FORMULA of the substance produced in higher amount at electrode Y. 9.4 A solution of zinc iodide, ZnI₂, is added to the electrolyte of this cell. What product(s) will be formed at 9.4.1 Electrode X? 9.4.2 Electrode Y?

A group of learners set up a standard galvanic cell, using cadmium and chlorine gas electrodes, as shown below. 8.1 Define the term galvanic cell. 8.2 For this cell, write down the: 8.2.1 Cell notation. 8.2.2 Direction of the electron flow. Choose from P TO Q or Q TO P. 8.2.3 Reduction half-reaction. 8.3 How will the reading on the voltmeter be affected when the concentration of the chloride ions is increased? Choose from INCREASES, DECREASES or REMAINS THE SAME. Give a reason for the answer.

According to the Arrhenius theory, an acid is: A. a source of H⁺ ions in water. B. a source of OH⁻ ions in water. C. a substance that can accept a proton. D. a substance that can donate a proton. A property of sodium nitrate solution, NaNO₃(aq), is that it is: A. acidic. B. basic. C. ampholytic. D. neutral. An iron rod, Fe(s), is placed in a beaker containing chromium(III) ions, Cr³⁺(aq). Which ONE of the following is the CORRECT combination of products formed? A. Fe²⁺(aq) and Cr(s). B. Fe²⁺(aq) and Cr²⁺(aq). C. Fe³⁺(aq) and Cr²⁺(aq). D. Fe³⁺(aq) and Cr(aq).