In: Chemistry
In a titration of a 100.0mL 1.00M NH3 solution with 1.00M HCl, what is the pH of the solution after the addition of 127 mL of HCl? Kb = 1.8 x 10-5 for NH3
millimoles of NH3 = 100 x 1 = 100
millimoles of HCl = 127 x 1= 127
NH3 + HCl ---------------------> NH4Cl
100 127 0 ----------------------------> initial
0 27 100 ------------------------> after reaction
here strong acid remained in the solution. so pH can be decided by strong acid
HCl millimoles remained = 27
HCl molarity = millimoles / total volume
= 27 / (100+127)
= 0.119 M
[H+] = 0.119M
pH = -log[H+]
pH = -log(0.119)
pH = 0.925