Question

There will be a short quiz held at the beginning of the lab session. The quiz will be based on some of the material shown below. 1. A student performed a titration on a 5.00 mL sample of an unknown HCl solution, using 10.90 mL of 0.09345 M NaOH from a buret and phenolphthalein indicator. What was the concentration of the unknown HCI? Use the correct number of sign ificant figures. 2. Another student designed a procedure to determine the concentration of a second unknown HCI solution to 4 significant figures. The student was given 100 mL of the HCl solution in a 250 mL beaker and told that the HCl was approximately 0.11 M. The student was also given phenolphthalein indicator and 250 mL of 0.1234 M NaOH The student filled a buret with the NaOH solution. The student then placed an appropriate volume of unknown HCl into a 250 mL Erlenmeyer flask and added a few drops of the indicator. The student had a choice of several pieces of glasswa re to use to transfer the appropriate volume of HCl solution from the 250 mL beaker into the Erlenmeyer flask. In the list of equipment shown below, place an "X" next to all of the glasswa re that is not appropriate for this task, assuming that all of the required HCl is transferred at once. To answer this question, consider the significant figures requirement and then calculate how many mL of NaOH is required to complete the titration when using the various listed items. You will have to show all your calculations on the quiz. 10 mL graduated cylinder 25 mL graduated cylinder 50 mL graduated cylinder 5 mL pipet 10 mL pipet 15 mL pipet 25 mL pipet 100 mL beaker

Answer 1

1 answer is

HCI acid, so volume = Va concentration Ma Naoh - Base, so volume - Vy concentration - My HC) NaoH Va = 5.0 me V = 10.90 me My = 0.09345M Mala = MOVE At neutralisation point > Ma = Molo substitute all the values 845M) (10.90 mi) 2 = 0.2037M (5 me) . Concentration of unknown HCl = 0.2037M & Hal concentration = 0.2037M = 0.204M