Electrochemistry

Oxidation Numbers and RedoxSign up

know what is meant by the term 'oxidation number' and understand the rules for assigning oxidation numbers · be able to calculate the oxidation number of elements in compounds and ions, including in peroxides and metal hydrides · be able to indicate the oxidation number of an element in a compound or an ion, using a Roman numeral · be able to write formulae given oxidation numbers · understand oxidation and reduction in terms of electron transfer and changes in oxidation number, and the application of these ideas to reactions of s-block and p-block elements · know that oxidising agents gain electrons and reducing agents lose electrons · understand that a disproportionation reaction involves an element in a single species being simultaneously oxidised and reduced · know that oxidation number is a useful concept in terms of the classification of reactions as redox and as disproportionation · understand that metals, in general, form positive ions by loss of electrons with an increase in oxidation number whereas non-metals, in general, form negative ions by gain of electrons with a decrease in oxidation number · be able to write ionic half-equations and use them to construct full ionic equations

Standard Electrode Potentials and the Hydrogen ElectrodeSign up

understand the terms 'oxidation' and 'reduction' in terms of electron transfer and changes in oxidation number, applied to s-, p- and d-block elements · know what is meant by the term 'standard electrode potential', E° · know that the standard electrode potential, E°, is measured in conditions of: (i) 298 K temperature; (ii) 100 kPa pressure of gases; (iii) 1.00 mol dm^-3 concentration of ions · know the features of the standard hydrogen electrode and understand why a reference electrode is necessary · understand that different methods are used to measure standard electrode potentials of: (i) metals or non-metals in contact with their ions in aqueous solution; (ii) ions of the same element with different oxidation numbers · CORE PRACTICAL 12: Investigating some electrochemical cells

Cell Potentials, Feasibility and the Nernst EquationSign up

be able to calculate a standard emf, E°_cell, by combining two standard electrode potentials · be able to write cell diagrams using the conventional representation of half-cells · understand the importance of the conditions when measuring an electrode potential, E · be able to use standard electrode potentials to predict the thermodynamic feasibility of a reaction · understand that E°_cell is directly proportional to the total entropy change and to ln K for a reaction · understand the limitations of predictions made using standard electrode potentials, in terms of kinetic stability of systems and departure from standard conditions · know that standard electrode potentials are sometimes referred to as standard reduction potentials and can be listed as an electrochemical series · understand how standard electrode potentials can be used to predict the thermodynamic feasibility of disproportionation reactions

Redox Titrations and Electrochemical CellsSign up

be able to carry out both structured and unstructured titration calculations involving redox reactions, including iron(II) ions and potassium manganate(VII) and sodium thiosulfate and iodine · be able to discuss the uncertainty of measurements and their implications for the validity of the final results · CORE PRACTICALS 13a and 13b: Carry out redox titrations with both: (i) iron(II) ions and potassium manganate(VII); (ii) sodium thiosulfate and iodine · understand that fuel cells use the energy released on the reaction of a fuel with oxygen to generate a voltage (knowledge that methanol and other hydrogen-rich fuels are used in fuel cells is expected) · know the electrode reactions that occur in a hydrogen-oxygen fuel cell (knowledge of hydrogen-oxygen fuel cells with both acidic and alkaline electrolyte is expected)

Electrolysis and Faraday CalculationsSign up

predict the products of electrolysis of molten and aqueous electrolytes · recall and use F = Le (the Faraday constant) and Q = It · calculate masses and volumes of products from charge passed (n = Q/zF) · explain selective discharge of ions at the electrodes