17.1 Buffers

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    A buffer is a solution that resists changes in pH.

    It is composed of a weak acid and its conjugate base or a weak base and its conjugate acid.

    Buffer Range = pKa ± 1

    Acid pKa
    HF 3.2
    CH3COOH 4.8
    H2CO3 6.4, 10.3
    H3PO4 2.1, 7.2, 12.4
    3 Ways to Prepare a Buffer
    Weak Acid / Conjugate Base
    1          :          1
    Weak Acid / Strong Base
    2          :          1
    Weak Base / Strong Acid
    2          :          1

    Calculations with buffers

    calcs with buffers

    (Henderson−Hasselbalch Equation)

    What is the pH of a solution having 0.10M CH3COOH and 0.080M CH3COONa? (Ka = 1.76×10-5)




    What would be the pH if 5.0mL of 0.10M HCl were added to 100mL of the buffer solution above?