Presentation on theme: "Redox Titration OF bleach"— Presentation transcript:
1 Redox Titration OF bleach Due Today:1. Redox Titration of Bleach Pre-Lab2. Copper Reduction Formal Lab ReportHomework:1. Redox Titration Short Report2. Gravimetric Analysis of Phosphorus Pre-LabRedox Titration OF bleach
2 ObjectiveDetermine the weight percent of sodium hypochlorite (NaOCl) in bleach via redox titration.
3 Key Terms Oxidation-Reduction (Redox) Reaction: Follow the transfer of electronsMatched reaction – you cannot have one without the other
4 Key TermsTitration – process of reacting a solution of unknown concentration with a solution of a known concentration until the reaction is JUST completeAll reactants are limiting
5 Key TermsEquivalence Point – equal quantities of opposite solutions existFor acid/base titrations:Moles of acid = Moles of baseFor redox titrations, you must you the reaction equation to determine moles
6 Procedure Notes Preparation of KIO3 Solution: Use 250 mL volumetric flaskBe precise!
7 Procedure Notes Standardization of (Na2S2O3): Rinse the buret with DI water and Na2S2O3 before you titratePIPETE KIO3 solutionDO NOT PIPET FROM VOLUMETRIC FLASK!!IMMEDIATELY titrate after KI is added
8 Procedure Notes During the Titration: Look for light yellow color Add starchBlue/BlackTitrate until clear1-5 drops3 good trialsMolarities within 5% of average
9 Procedure Notes Titration of Bleach During the Titration: Weigh 2.000g of bleachDuring the Titration:Immediately titrate when you add KILook for light yellow color
10 Procedure Notes Add starch Titrate until clear 3 good trials Blue/BlackTitrate until clear1-5 drops3 good trialsMolarities within 5% of averageRECORD THE REPORTED MASS NaOCl FROM THE BLEACH BOTTLE!!!!!!!
17 Redox equation example 3. Determine which species is oxidized and reduced𝐶𝑢𝑆𝑂 4 𝑎𝑞 +𝑍𝑛 𝑠 → 𝑍𝑛𝑆𝑂 4 𝑎𝑞 +𝐶𝑢(𝑠)Cu : +2S : +4O : -8Zn: 0Cu: 0Zn : +2Zn: 0→+2 loss of electronsZinc is oxidized and is the reducing agentCu: +2→0 gain electronsCopper is reduced and is the oxidizing agent