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A buffer solution contains 0.283 M hypochlorous acid and 0.456 M potassium hypochlorite.

If 0.0464 moles of perchloric acid are added to 225 ml of this buffer, what is the pH of the resulting solution ?
(Assume that the volume change does not change upon adding perchloric acid)

pH =

  • chemistry -

    millimols HOCl = mL x M = 225 x 0.283 = estimated 64.
    mmols KOCl = 225 x 0.456 = 103
    add 46 mmols HClO4.
    ..........OCl^- + H^+ ==> HOCl + H2O
    I.........64......0........103
    add..............46.............
    C........-46....-46.........+46
    E.........18......0........149

    Substitute the E line into the Henderson-Hasselbalch equation and solve for pH. You will need to look up or calculate pKa for HOCl
    Note that I have rounded on all of the numbers. You will need to recalculate and obtain more accurate numbers.

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