# 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
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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