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CHEMISTRY LEVEL 3


1. GAS LAWS
2. THE MOLE: Formulae and Chemical Equations
3. ORGANIC CHEMISTRY 1
4. NITROGEN AND ITS COMPOUNDS
5. SULPHUR AND ITS COMPOUNDS
6. CHLORINE AND ITS COMPOUNDS
7. A guide to chemical tests based on this module
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THE MOLE: Formulae and Chemical Equations: Redox titration



2.0 THE MOLE: Empirical and Molecular formula


2.12 Redox titration

Redox titrations involve both reduction and oxidation reactions at the same time. The procedure is similar to that of neutralization processes (Section 2.11).


Examples are the reactions between acidified potassium manganate (VII) or potassium chromate (VI) as oxidizers, and iron (II), bromide, iodide, sulphite, sulphide, and thiosulphate ions as reducers.


The end-point of a redox titration is sharply marked by a slight excess of one reactant; so it does not need an indicator. In titrating manganate (VII) ions (MnO4-) against sulphite ions (SO32-), for example, end-point is marked by the single extra drop of manganate (VII) ions which suddenly turns the mixture purple or pink (Figure 2.12).


Redox titration, chemistry demonstrations, gas laws, high school chemistry

Figure 2.12: Redox titration involving SO32- and MnO4- ions