Chemistry

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A buffer system contains 0.25M NH4+ and 0.19M NH3. pka of NH4 is 9.25.

How many moles of NaOH must be added to 1.00L of this solution to increase the pH to 9.25?

  • Chemistry -

    mol NH3 = M x L = 0.19*1 = 0.190
    mol NH4^+ = 0.25*1 = 0.250
    -----------------
    ........NH4^+ + OH^- ==> NH3 + H2O
    I.....0.250.....0......0.190
    add..............x............
    C.......-x......-x.......+x
    E.....0.250-x.....0......0.190+x
    Substitute into the Henderson-Hasselbalch equation and solve for x = mol NaOH added to 1L buffer to make pH = 9.25

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