Analysis of Commercial Bleach Lab
Analysis of Commercial Bleach Lab I. Purpose
In this experiment, the amount of sodium hypochlorite in a commercial bleach will be determined by reacting it with sodium thiosulfate in the presence of iodide ions and starch. A solution of sodium thiosulfate of known concentration will be added to the bleach using a buret in a titration procedure. The disappearance of the dark blue color of the starch-iodine complex will signal the end point. II. Procedures
Pre-Lab Questions 1. What is meant by a “titration”?
Titration is a technique where a solution of known (acid or base) concentration is used to determine the concentration of an unknown (acid or base) solution.
2. A solution of household vinegar (a mixture of acetic acid and water) is to be analyzed. A pipet is used to measure out 10.0 mL of the vinegar, which is placed in a 250-mL volumetric flask. Distilled water is added until the total volume of solution is 250 mL. A 25.0-mL portion of the diluted solution is measured out with a pipet and titrated with a standard solution of sodium hydroxide.
The neutralization reaction is as follows:
HC2H3O2(aq) + OH-(aq) → C2H3O2-(aq) + H2O(l)
It is found that 16.7 mL of 0.0500 M NaOH is needed to titrate 25.0 mL of the diluted vinegar.
Calculate the molarity of the diluted vinegar.
Molarity=Moles/Volume
Moles = Molarity x Volume
(.0500 M NaOH)(16.7 mL) = ( x M diluted vinegar)( 25.0 mL) x M diluted vinegar = .0334 M diluted vinegar
3. Calculate the molarity of the household vinegar.
Molarity = Moles/Volume
Moles = Molarity x Volume
(.0334 M diluted vinegar)(250 mL of diluted vinegar) = ( x M household vinegar)( 10.0 mL of Household vinegar) x M household vinegar = (.0334 M diluted vinegar x 250 mL of diluted vinegar)/ 10.0 mL of Household Vinegar x M household vinegar = .835 M
4. The household vinegar has a density of 1.05g/mL. Calculate the percent by mass of acetic acid in the household vinegar.
(.835 mol/1 L) x (1L/1000mL)
In this experiment, the amount of sodium hypochlorite in a commercial bleach will be determined by reacting it with sodium thiosulfate in the presence of iodide ions and starch. A solution of sodium thiosulfate of known concentration will be added to the bleach using a buret in a titration procedure. The disappearance of the dark blue color of the starch-iodine complex will signal the end point. II. Procedures
Pre-Lab Questions 1. What is meant by a “titration”?
Titration is a technique where a solution of known (acid or base) concentration is used to determine the concentration of an unknown (acid or base) solution.
2. A solution of household vinegar (a mixture of acetic acid and water) is to be analyzed. A pipet is used to measure out 10.0 mL of the vinegar, which is placed in a 250-mL volumetric flask. Distilled water is added until the total volume of solution is 250 mL. A 25.0-mL portion of the diluted solution is measured out with a pipet and titrated with a standard solution of sodium hydroxide.
The neutralization reaction is as follows:
HC2H3O2(aq) + OH-(aq) → C2H3O2-(aq) + H2O(l)
It is found that 16.7 mL of 0.0500 M NaOH is needed to titrate 25.0 mL of the diluted vinegar.
Calculate the molarity of the diluted vinegar.
Molarity=Moles/Volume
Moles = Molarity x Volume
(.0500 M NaOH)(16.7 mL) = ( x M diluted vinegar)( 25.0 mL) x M diluted vinegar = .0334 M diluted vinegar
3. Calculate the molarity of the household vinegar.
Molarity = Moles/Volume
Moles = Molarity x Volume
(.0334 M diluted vinegar)(250 mL of diluted vinegar) = ( x M household vinegar)( 10.0 mL of Household vinegar) x M household vinegar = (.0334 M diluted vinegar x 250 mL of diluted vinegar)/ 10.0 mL of Household Vinegar x M household vinegar = .835 M
4. The household vinegar has a density of 1.05g/mL. Calculate the percent by mass of acetic acid in the household vinegar.
(.835 mol/1 L) x (1L/1000mL)