A solid weak acid is weighed, dissolved in water and diluted to exactly 50.00 ml. 25.00 ml of the solution is taken out and is titrated to a neutral endpoint with 0.10 M NaOH. The titrated portion is then mixed with the remaining untitrated portion and the pH of the mixture is measured.
Mass of acid weighed out (grams) 0.799
Volume of NaOH required to reach endpoint: (ml) 18.0
pH of the mixture (half neutralized solution) 3.73
Calculate the following
1) What is the pKa of the acid?
2) What is the molarity of the original acid solution?
3) What is the molecular weight of the acid?
2 HA + NaOH ..........> NaA + H 2 O Moles of HA = 18/1000 x 0.10 = 0.0018 moles... View the full answer