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    Electrochemistry: Oxidation Reactions

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    Please explain how to do these E-chem reactions.

    Set 1:

    Find the standard reduction potential for the reaction (it's a range based off results)

    VO3-(aq) + 4H+(aq) + e- → VO2+(aq) + 2H2O(l) Ecell=??

    Results for my reactions any heat that is mentioned was for 12-15 minutes

    Vanadyl Sulfate (blue solution):

    1.) 20 drops of 3% H2O2: initially turned brown and then pale green after heat
    2.) 40 drops of Bromine water: initially green then light blue/green after heat
    3.) 20 drops of 0.2M NaNO3: initially blue and after heat blue
    4.) 20 drops of Fe2(SO4)3: initially blue and after heat green
    5.) 20 drops of 0.2M Na2SO4: initially blue then after heat still blue
    6.) control tube

    Ammonium Vanadate (yellow solution):

    1.) pea size amount of amount solid Na2SO3: turned cloudy blue then clear blue
    2.) 20 drops of distilled water: no reaction and no heat
    3.) 20 drops of 0.2M NaBr: no reaction and no change after heat
    4.) 20 drops of 0.2M NaNO2: turned pale green/blue and light blue after heat
    5.) pea size amount of Fe(NH4)2(SO4)2 *6H2O: turned turquoise immediately
    6.) 20 drops of H2C2O4: no reaction initially but turned blue after heat
    7.) control tube

    I have to find the range of the above reaction based on the results we obtained, my lab book does not explain how to go about finding this range and I am at a loss at how to do it.

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    Solution Preview

    The goal is to determine whether or not a reaction occurred based on your observations. For a reaction to occur, the final voltage has to be >0. Take the first reaction for example. Peroxide changing to water provides a potential of 1.77 V and takes 2 e-. The half-reaction to balance this would be:

    VO(+2) + H2O --> VO2(+1) + 2H+ + e-

    because it gives off ...

    Solution Summary

    This solution explains how to solve problems related to oxidation reactions and electrochemistry.