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    Why is sulphuric acid used in the standard titration with potassium manganate to find the concentration of Fe2+ in a sample of whatever? I know it reduces the manganate ion to Mn2+, and reduces Fe2+ to Fe3+, but how does this help?

    Edit: OXIDISES Fe2+ to Fe3+
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    sulphuric acid is used to provide the acidic medium needed so that Mn(VII) can be reduced to Mn(II)

    Redox potentials depend on the pH - in alkali solution the Mn(VII) is not such a good oxidising agent.

    The H+ ions do NOT oxidise or reduce anything - they DO mop up the oxygens during the overall reaction. However this 'reaction'

    MnO4(-) + 8H+ +5e --> Mn(2+) + 4H2O

    is just a half equation it DOES NOT mean that it can proceed on its own. It must be associated with another half equation (that of the reducing agent - in this case Fe2+)

    those 5 electrons on the left hand side MUST come from a reducing agent for the process to work.
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    (Original post by charco)
    sulphuric acid is used to provide the acidic medium needed so that Mn(VII) can be reduced to Mn(II)

    Redox potentials depend on the pH - in alkali solution the Mn(VII) is not such a good oxidising agent.

    The H+ ions do NOT oxidise or reduce anything - they DO mop up the oxygens during the overall reaction. However this 'reaction'

    MnO4(-) + 8H+ +5e --> Mn(2+) + 4H2O

    is just a half equation it DOES NOT mean that it can proceed on its own. It must be associated with another half equation (that of the reducing agent - in this case Fe2+)

    those 5 electrons on the left hand side MUST come from a reducing agent for the process to work.
    Gotcha - thanks
 
 
 
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