A student pipetted five 25.00 milliliter samples of hydrochloric acid and transferred each sample to an Erlenmeyer flask, diluted it with distilled wa­ter, and added a few drops of phenolphthalein to each. Each sample was then titrated with a sodium hy­droxide solution to the appearance of the first per­manent faint pink color. The following results were obtained.
Volumes of NaOH Solution
First Sample35.22 mL
Second Sample36.14 mL
Third Sample36.13 mL
Fourth Sample36.15 mL
Fifth Sample36.12 mL
Which of the following is the most probable explanation for the variation in the student's results?
A) The burette was not rinsed with NaOH solution.
B) The student misread a 5 for a 6 on the burette when the first sample was titrated.
C) A different amount of water was added to the first sample.
D) The pipette was not rinsed with the HCI solution. If the pipet were initialed rinsed with water and then not
rinsed again with the HCl solution, in the first trial the HCl was diluted by the water and thus less NaOH was
required to titrate
E) The student added too little indicator to the first sample.