Experiment 5: Anions And Redox Reactions

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Experiment 5: Anions and Redox Reactions
(a) Objectives
General: To examine the importance of potassium permanganate as an oxidising agent and the strong powers of halogens in oxidation.
Part 1
Determining the colour associated with a certain halogen by adding a sample of the halogen to cyclohexane and recording the colours observed.
Part 2
Identifying a halogen referring to the colours recorded in part 1, by reacting the halogen with a halide and observing the colour present.
Part 3
Recording observing the physical changes that occur when an oxyanion, is tested using, i) Dilute HNO3, ii) Dilute AgNO3 and then acid, iii) BaCl2 and then acid, iv) Ammonium molybdate and if a percip. was seen is part iii) then dilute Nitric acid.
Part 4
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Oxyanions are anions which contain oxygen.
Part 5.
Determination of % of Fe (II) in a salt redox titration.
A titration is a quantitative analysis. From a titration the concentration of a given sample, in this case Fe(II) can be found by using a standard compound of whose concentration is known, in this example: 0.02M of KMnO4.
A redox titration involves an oxidation-reduction reaction, hence the name redox.
Redox reactions involve the transfer of electrons, i.e. the loss and gain of electrons.
KMnO4 is an oxidising agent which means it brings about oxidation and therefore it is being reduced. This means that the Fe (II) is the reducing agent and therefore is being oxidised.
Carrying out a redox titration means for this experiment, using the average titre, which is determined by the colour change of the end point, it can determine: The moles of KMNO4 in the average titre, the amount of moles needed of Fe(II) to complete the reaction in 25cm3, using the Balanced equation for the reaction, from this the amount of Fe (II) in volumetric flask. Using these values the weight of Fe (II) can be calculated and then the % weight, respectively.

Experimental Procedure

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