Lab This procedure is one type of redox titration known as an iodometric analysis. In the first step, excess potassium iodide is added to a solution of bleach and is oxidized to iodine by the hypochlorite ion. Acetic acid is added to provide the hydrogen ion needed for the reaction. CIO +2H+ + 21- ----- 12 + CI- + H2O The amount of iodine formed by this reaction is found by titrating with sodium thiosulfate solution. 12 + 2S2032---- 21- + S4062- Step 1 Use 5ml pipet to measure out a sample of a laundry bleach and transfer to a 250ml volumetric flask. Using the density of bleach (1.11g/cm°) determine the mass of the 5ml sample. Step 2 Fill the buret with the sodium thiosulfate solution. The concentration of the sodium thiosulfate solution is 0.100M. Step 3 Place 50ml of bleach solution into a flask. Add a stir bar and stir the solution gently using the stir plate. Step 4 Add 2 gr of potassium iodide to the flask. The amount added does not have to be precise. Add 10ml of glacial acetic acid Step 5 Add about 2ml of the starch indicator Step 6 Titrate slowly until the blue color disappears. Document the value when the blue color disappears. Blue color disappears at 17.5ml Q 1. Calculate the moles of sodium thiosulfate used. 2. Calculate the moles of iodine formed. 3. Calculate the moles of NaCIO in the original sample. Oxidizing Power of Laundry Bleach

Chemistry

9th Edition

ISBN:9781133611097

Author:Steven S. Zumdahl

Publisher:Steven S. Zumdahl

Chapter15: Acid-base Equilibria

Section: Chapter Questions

Problem 13Q: An acid is titrated with NaOH. The following beakers are illustrations of the contents of the beaker...

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Question

1. Calculate the moles of sodium thiosulfate used.

2. Calculate the moles of iodine formed.

3. Calculate the moles of NaClO in the original sample. Oxidizing Power of Laundry Bleach Westminster College SIM 5

4. Convert the moles of NaClO to mass of NaClO.

5. Determine the mass of NaClO per gram of bleach.

6. Calculate the percent NaClO in the brand of bleach.

Transcribed Image Text:Lab This procedure is one type of redox titration known as an iodometric analysis. In the first step, excess potassium iodide is added to a solution of bleach and is oxidized to iodine by the hypochlorite ion. Acetic acid is added to provide the hydrogen ion needed for the reaction. CIO +2H+ + 21- ----- 12 + Cl- + H2O The amount of iodine formed by this reaction is found by titrating with sodium thiosulfate solution. 12 + 2S2032- ----- 21- + S4062- Step 1 Use 5ml pipet to measure out a sample of a laundry bleach and transfer to a 250ml volumetric flask. Using the density of bleach (1.11g/cm³) determine the mass of the 5ml sample. Step 2 Fill the buret with the sodium thiosulfate solution. The concentration of the sodium thiosulfate solution is 0.100M. Step 3 Place 50ml of bleach solution into a flask. Add a stir bar and stir the solution gently using the stir plate. Step 4 Add 2 gr of potassium iodide to the flask. The amount added does not have to be precise. Add 10ml of glacial acetic acid Step 5 Add about 2ml of the starch indicator Step 6 Titrate slowly until the blue color disappears. Document the value when the blue color disappears. Blue color disappears at 17.5ml 1. Calculate the moles of sodium thiosulfate used. 2. Calculate the moles of iodine formed. 3. Calculate the moles of NaCIO in the original sample. Oxidizing Power of Laundry Bleach 4. Convert the moles of NaCIO to mass of NaCIO. 5. Determine the mass of NaCIO per gram of bleach. 6. Calculate the percent NaCIO in the brand of bleach.

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