HowMuchHydrogenPeroxideisinBleach - How Much Hydrogen...

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How Much Hydrogen Peroxide is in Bleach? CHM 116 General Chemistry II Arizona State University Lab 5 Group #5 April 11, 2017 Introduction:
The goal of this lab was to learn about redox reactions through a titration of a bleach solution. A titration is a certain type of experiment in chemistry in which a solution is added from a buret to a beaker. In this case, the concentration of the solution in the beaker was known, and the concentration of the solution in the buret was unknown. By titrating (slowly adding solution from the buret to the beaker) the solution till the equivalence point was reached, the concentration of the solution in the buret could be determined. The equivalence point is almost always determined by a color change in the solution. The end goal of this experiment was to determine the percent by mass of H 2 O 2 (hydrogen peroxide) in the bleach solution. In part 1, potassium permanganate (KMnO 4 ) was standardized to determine its concentration. Standardization is a very important process because it determines the exact molar concentration of a chemical used throughout the experiment. In many cases, the exact concentration is not known. For this reason, chemicals from the storeroom cannot be used in precise experiments like titrations. Thus, the standardization process is done, which enables the experimenters to determine the exact concentration of the solution. In this standardization reaction, MnO 4 - ions are reduced to Mn 2+ , and Fe 2+ ions are oxidized to Fe 3+ . In order to make the reaction occur, excess sulfuric acid must be added to the solution to provide H + ions. The balanced net ionic reaction for this part was: MnO 4 - (aq) + 5Fe 2+ (aq) + 8H + (aq) → Mn 2+ (aq) + 5Fe 3+ (aq) + 4H 2 O (l) In part 2, bleach was analyzed to determine the H 2 O 2 content. The bleach is once again combined with excess acid, then titrated with the now known concentration of potassium permanganate. In this reaction, H 2 O 2 is the reducing agent because it is oxidized. KMnO 4 is once again the oxidizing agent because it is reduced. The balanced net ionic reaction for this part was: 2MnO 4 - (aq) + 5H 2 O 2 (aq) + 6H + (aq) → 2Mn 2+ (aq) + 5O 2 (g) + 8H 2 O (l)
Experimental: In order to find out how much H

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