Analysis of Commercial Bleach

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Analysis of a Commercial Bleach Lab Guidelines • Name, Exp. Name, Number, Date (we did lab), Partner(s) • Purpose • Compound Names, Formulas, and Molar Masses (5 used – no formula or molar mass for starch) • Reactions (use the four listed on the front page of the lab) • Procedure/Observations • Include initial observations and final observations/odors, masses of KI… • Results (Data Table) • Make a table that has your data of KI masses, and the three volumes (from the three trials) needed to titrate the bleach • Calculations (Data and Calculations Section in lab) 1. Use the equations given on the front page to determine the number of moles of sodium thiosulfate that are equivalent to one mole of sodium hypochlorite. 2. From your three trials, calculate the average volume of Na2S2O3 needed for the titration of 25.00mL of diluted bleach. 3. Use the average volume and the molarity of Na2S2O3 to determine the molarity of the diluted bleach. (Find moles of Na2S2O3, convert to moles of NaClO, and divide by volume of dilute bleach that was titrated in each trial to get M). 4. Calculate the molarity of the commercial bleach (not diluted) using your answer from step 3 and the M¬1V1 = M2V2 equation. (Use volume of concentrated bleach and total volume of dilute bleach) 5. Assume that the density of the commercial bleach is 1.08g/mL. Calculate the percent by mass of NaClO in the commercial bleach. (Start with molarity of concentrated NaClO found in part 4. Determine the molarity per mL instead of liter. Next, divide by the density (you’ll have a label of mole/g at this point). Then multiply this by the molar mass of NaClO which has a label of g/mol so all labels cancel. Finally multiply by 100 to get a percent!) 6. The label on the commercial bleach reports the percent by mass NaClO to be 6.0%. Calculate the percent error of your value, assuming that the

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