All requirements are not given: Assuming some values: No of moles of HCl = 100 x 0.2 /1000 = 0.02 No of moles of NaOH = 50 x 0.250 / 1000 = 0.0125 moles HCl in excess = 0.02 - 0.0125 = 0.0075 Total volume = 150 mL Converting mL into L= 150mL = 0.150 L [H+] = 0.0075 / 0.150 = 0.05 M As, pH is the negative log of hydrogen ion concentration: pH = - log 0.05 = 1.30 at equivalence point Concentration of hydroxyl ions is equal to Concentration of Hydrogen ions: [OH-] = [H+] so pH = 7
