- Based on your titration data and calculations for determination 1:
(1) Calculate the volume of Na 2 S 2 O 3 solution required had you transferred commercial
bleaching solution instead of diluted bleaching solution to the Erlenmeyer flask 1.
25 mL commercial bleaching solution was diluted by a factor of 10 and required
19 mL of Na 2 S 2 O 3. A 25 mL undiluted commercial bleaching solution would require
ten times more Na 2 S 2 O 3. Approximately 190 mL of Na 2 S 2 O 3 would be required for
titration.
(2) Assuming you used only the glassware supplied for the original experiment, briefly
comment on the procedural change necessary to titrate 25.00 mL of commercial
bleaching solution.
The procedural change would be to titrate the solution a portion at a time and then
calculate the total Na 2 S 2 O 3 used.
(3) Would you anticipate a greater error in the results of an analysis done in this way
than is the case with the standard procedure? Briefly explain.
I would anticipate greater error in the results of an analysis done this way than in the stan-
dard procedure due to there being too many opportunities for misreading and miscalcula-
tion to occur. - Commercial bleaching solutions found on store shelves are usually labeled: “Contains at
least 5.25% sodium hypochlorite.” Analysis will often show a lower OCl–ion content.
Briefly explain.
Analysis will show a lower OCl–ion content on commercial bleaching solutions because it
is exposed to air and the solution becomes diluted.
- Student from College of the Canyons, Santa Clarita, CA. The lab write-up is provided to show format only. No guarantee is provided
for accuracy or quality of answers.
** Chemical Education Resources, Inc., “Determining the Percent Solium Hypochlorite in Commercial Bleaching Solutions,” Palmyra, PA.,
Part III: AP Chemistry Laboratory Experiments