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100.0 mL buffer solution contains 0.500 M HClO (Ka= 2.9x10^-8) and 0.450 KClO. W

ID: 1044611 • Letter: 1

Question

100.0 mL buffer solution contains 0.500 M HClO (Ka= 2.9x10^-8) and 0.450 KClO. What is the initial pH of the buffer solution? What is the pH of the solution after the addition of 0.0050 moles of HBr? What is the pH of the solution after the addition of 0.010 moles of KOH? 100.0 mL buffer solution contains 0.500 M HClO (Ka= 2.9x10^-8) and 0.450 KClO. What is the initial pH of the buffer solution? What is the pH of the solution after the addition of 0.0050 moles of HBr? What is the pH of the solution after the addition of 0.010 moles of KOH? What is the initial pH of the buffer solution? What is the pH of the solution after the addition of 0.0050 moles of HBr? What is the pH of the solution after the addition of 0.010 moles of KOH? What is the pH of the solution after the addition of 0.0050 moles of HBr? What is the pH of the solution after the addition of 0.010 moles of KOH?

Explanation / Answer

no of moles of HClO = molarity * volume in L

                               = 0.5*0.1 = 0.05moles

no of moles of KClO    = molarity * volume in L

                                 = 0.45*0.1     = 0.045mole

PKa     = -logKa

         = -log2.9*10^-8

        = 7.5376

PH      = Pka + log[KClO]/[HClO]

           = 7.5376 + log0.045/0.05

            = 7.5376 -0.04575    = 7.4918

no of moles of KClO after addition of 0.005 moles of HBr    =0.045-0.005 = 0.04moles

no of moles of HClO after addition of 0.005moles of HBr = 0.05+0.005    = 0.055moles

PH     = PKa + log[KClO]/[HClO]

         = 7.5376 + log0.04/0.055

        = 7.5376 -0.1383   = 7.3993

no of moles of KClO after addition of 0.01 moles of KOH    =0.045+0.01 = 0.055moles

no of moles of HClO after addition of 0.01moles of HBr = 0.05-0.01    = 0.04moles

PH     = PKa + log[KClO]/[HClO]

         = 7.5376 + log0.055/0.04

        = 7.5376 +0.1383   = 7.6759