Two students titrate different samples of the same solution of HCl using 0.100 M NaOH solution and phenolphthalein indicator (Figure 4.12). The first student pipets 20.0 mL of the HCl solution into a flask, adds 20 mL of distilled water and a few drops of phenolphthalein solution, and titrates until a lasting pink color appears. The second student pipets 20.0 mL of the HCl solution into a flask, adds 60 mL of distilled water and a few drops of phenolphthalein solution, and titrates to the first lasting pink color. Each student correctly calculates the molarity of an HCl solution. What will the second student’s result be 

(a) Four times less than the first student’s result
(b) Four times greater than the first student’s result
(c) Two times less than the first student’s result
(d) Two times greater than the first student’s result
(e) The same as the first student’s result

Data given in Figure 4.12

Transcribed Image Text:

Buret containing a base of known concentration Flask containing aque- ous solution of sample being analyzed and an indicator A Base added from buret 125 100 75 1 A buret, a volumetric measuring device calibrated in divisions of 0.1 mL (and consequently read to the nearest 0.01 mL), is filled with an aqueous solution of a base of known concentration. Figure 4.12 Titration of an acid in aqueous solution with a base. 2 Base is added slowly from the buret to the solution containing the acid being analyzed and an indicator. -100 3 When the amount of NaOH added from the buret equals the amount of H30+ supplied by the acid (the equivalence point), the dye (the indicator) changes color. (The indicator used here is phenolphthalein.) Photos Cengage Learning/Charles D. Winters