Redox Chemistry structured questions · SEC G3 Pure Chemistry

Learning objectives

• define oxidation and reduction (redox) in terms of oxygen/hydrogen gain/loss
• define redox in terms of electron transfer and changes in oxidation state
• identify redox reactions in terms of oxygen/hydrogen gain/loss, electron gain/loss and changes in oxidation state
• describe the use of aqueous potassium iodide and acidified potassium manganate(VII) in testing for oxidising and reducing agents from the resulting colour changes.
• 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
• 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
• describe, in terms of the mobility of ions present and the electrode products, the electrolysis of molten sodium chloride, using inert electrodes
• predict the likely products of the electrolysis of a molten binary ionic compound using inert electrodes
• apply the idea of selective discharge based on — cations: linked to the reactivity series (see also 8.4)
• apply the idea of selective discharge based on — anions: halides, hydroxides and sulfates (e.g. aqueous copper(II) sulfate and dilute sodium chloride solution (as essentially the electrolysis of water))
• apply the idea of selective discharge based on — concentration effects (as in the electrolysis of concentrated and dilute aqueous sodium chloride) (in all cases above, inert electrodes are used)
• predict the likely products of the electrolysis of an aqueous electrolyte, given relevant information
• construct ionic equations for the reactions occurring at the electrodes during the electrolysis, given relevant information
• describe the electrolysis of aqueous copper(II) sulfate with copper electrodes as a means of purifying copper (no technical details are required)
• describe the electroplating of metals, e.g. copper plating, and state one use of electroplating
• describe the production of electrical energy from simple cells (i.e. two electrodes in an electrolyte) linked to the reactivity series (see also 8.4) and redox reactions (in terms of electron transfer)
• describe hydrogen, derived from water or hydrocarbons, as a potential fuel, reacting with oxygen to generate electricity directly in a hydrogen fuel cell (details of the construction and operation of a fuel cell are not required).