3/2/2017 11:55 PM A 2.5/5 2/27/2017 09:23 PM Gradebook Print Calculator Periodic

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3/2/2017 11:55 PM A 2.5/5 2/27/2017 09:23 PM Gradebook Print Calculator Periodic Table Question 3 of 4 Map A Sapling Learning A buffered solution containing dissolved a C6H5NH2, and aniline hydrochloride, C6H5NH3Cl, has a pH of 5.50. a) Determine the concentration of C6H5 n the solution if the concentration of C6H5NH2 is 0.245 M. The pKb of aniline is 9.13. Number C He NH. b) Calculate the change in pH of the solution, ADH, if 0.391 g NaOH is added to the buffer for a final volume of 1.50 L. Assume that any contribution of NaoH to the volume is negligible. Number ApH AO Previous Give Up & View Solution Check Answer Next Ext Hint

Explanation / Answer

POH    = Pkb + log[C6H5NH3+]/[C6H5NH2]

5.5      = 9.13 + log[C6H5NH3+]/0.245

log[C6H5NH3+]/0.245   = 5.5-9.13

log[C6H5NH3+]/0.245   = -3.63

[C6H5NH3+]/0.245     = 10^-3.63

[C6H5NH3+]/0.245     = 0.000234

[C6H5NH3+]              = 0.000234*0.245 = 0.00005733M

b. molarity of NaOH = 0.391/40*1.5   = 0.00651M

molarity of C6H5H3^+     = 0.00005733 - 0.00651   = 0.00656M

molarity of C6h5NH2      = 0.245+0.00651               = 0.251 M

PH = PKb + log[C6H5NH3+]/[C6H5NH2]

      = 9.13 + log0.00656/0.251

       = 9.13-1.582   = 7.548

Chnge in PH   = 7.548-5.5 = 2.048

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