Question

Calculate the pH during the titration of 40.00 ml of 0.1000 M KOH with 0.1000 M HBr solution after the following additions of acid.

A) 29.00 ml
B) 39.00 ml
C) 48.00 ml

Answer 1

KOH                                                  HBr

MB =0.1M                                    MA = 0.1M

VB = 40ml                                   VA = 29ml

Molarity of mixed solutionM = MBVB- MAVA/VA+VB

                                               = 0.1*40-0.1*29/40+29 = 0.016M

POH   = -logM

        = -log0.016 =1.79

PH = 14- POH

    = 14 -1.79 =12.21

B.

KOH                                                  HBr

MB =0.1M                                    MA = 0.1M

VB = 40ml                                   VA = 39ml

Molarity of mixed solutionM = MBVB- MAVA/VA+VB

                                               = 0.1*40-0.1*39/40+29 = 0.00145M

POH   = -logM

        = -log0.00145 =2.84

PH = 14- POH

    = 14 -2.84 =11.16

KOH                                                  HBr

MB =0.1M                                    MA = 0.1M

VB = 40ml                                   VA = 48ml

Molarity of mixed solutionM = MAVa- MBVB/VA+VB

                                               = 0.1*48-0.1*40/40+29 = 0.0116M

PH = -logM

        = -log0.0116 =1.935