TJC 2025 IP4 Electrochemistry Notes (Student) (2)

2025 IP4 Chemistry Topic 11: Electrochemistry Notes Learning objectives At the end of this notes, you should be able to: (a) Describe electrolysis as the conduction of electricity through an ionic compound (an electrolyte), when molten or dissolved in water, leading to chemical changes (including decomposition) at the electrodes (b) Describe electrolysis as evidence for the existence of ions which are held in a lattice when solid but which are free to move when molten or in solution (c) Describe, in terms of the mobility of ions present and the electrode products, the electrolysis of molten sodium chloride, using inert electrodes (d) Predict the likely products of the electrolysis of a molten binary ionic compound using inert electrodes (e) Apply the idea of selective discharge based on (i) cations: linked to the reactivity series (ii) anions: halides, hydroxides and sulfates (e.g. aqueous copper(II) sulfate and dilute sodium chloride solution (as essentially the electrolysis of water)) (iii) concentration effects (as in the electrolysis of concentrated and dilute aqueous sodium chloride).(In all cases above, inert electrodes are used.) (f) Predict the likely products of the electrolysis of an aqueous electrolyte, given relevant information (g) Construct ionic equations for the reactions occurring at the electrodes during the electrolysis, given relevant information (h) Describe the electrolysis of aqueous copper(II) sulfate with copper electrodes as a means of purifying copper (no technical details are required) (i) Describe the electroplating of metals, e.g. copper plating, and state one use of electroplating (j) Describe the production of electrical energy from simple cells (from two electrodes in an electrolyte) linked to the reactivity series and redox reactions (in terms of electron transfer) (k) 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)

2 Topic Outline 1 Introduction to Electrolysis 1.1 Definition 1.2 Components of an electrolytic cell 1.2.1 Electrolyte 1.2.2 Electrodes 1.2.3 Set-up of an Electrolytic cell 2 Electrolysis of Molten Ionic Compounds 2.1 Electrolysis of molten sodium chloride 3 Electrolysis of Aqueous Ionic Compounds 3.1 Electrolysis of water 3.2 Electrolysis of dilute sodium chloride 3.3 Electrolysis of concentrated sodium chloride (brine) 3.4 Identification test for gases 4 Ease of Discharge 4.1 Ease of discharge of cations 4.2 Ease of discharge of anions 5 Nature of the Electrodes 5.1 Electrolysis of copper(II) sulfate solution using inert electrodes 5.2 Electrolysis of copper(II) sulfate solution during copper electrodes 6 Applications of Electrolysis 6.1 Electroplating 6.2 Purification of copper 7 Galvanic Cell 7.1 Definit