An acetic acid–sodium acetate buffer of pH 5.00 is 0.100 M in NaOAc. Calculate the pH after the addition of 10mL of 0.1 M ?

NaOH to 100mL of the buffer.

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  • 1 month ago

    Initial buffer composition:

    pH = pKa + log [NaOAC]/[HAc]

    5.00 = 4.74 + log (0.100/x)

    log (0.100/x) = 0.26

    x = 0.055 M HAc

    Addition of 10 ml (0.01 L) of 0.1 M NaOH = 0.001 moles NaOH

    HAc +  NaOH  ===>  NaOAc  +  H2O

    0.055....0.001.............0.100........Initial

    -0.001...-0.001..........+0.001......Change

    0.054........0................0.101.....Equilibrium

    pH = pKa + log (0.101/0.054)

    pH = 4.74 + 0.27

    pH = 5.01

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