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Redox Titration OF bleach

Due Today: 1. Redox Titration of Bleach Pre-Lab 2. Copper Reduction Formal Lab Report Homework: 1. Redox Titration Short Report 2. Gravimetric Analysis of Phosphorus Pre-Lab. Redox Titration OF bleach . Objective.

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Redox Titration OF bleach

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  1. Due Today: 1. Redox Titration of Bleach Pre-Lab 2. Copper Reduction Formal Lab Report Homework: 1. Redox Titration Short Report 2. Gravimetric Analysis of Phosphorus Pre-Lab Redox Titration OF bleach

  2. Objective • Determine the weight percent of sodium hypochlorite (NaOCl) in bleach via redox titration.

  3. Key Terms • Oxidation-Reduction (Redox) Reaction: • Follow the transfer of electrons • Matched reaction – you cannot have one without the other

  4. Key Terms • Titration – process of reacting a solution of unknown concentration with a solution of a known concentration until the reaction is JUST complete • All reactants are limiting

  5. Key Terms • Equivalence Point – equal quantities of opposite solutions exist • For acid/base titrations: Moles of acid = Moles of base • For redox titrations, you must you the reaction equation to determine moles

  6. Procedure Notes • Preparation of KIO3 Solution: • Use 250 mL volumetric flask • Be precise!

  7. Procedure Notes • Standardization of (Na2S2O3): • Rinse the buret with DI water and Na2S2O3 before you titrate • PIPETE KIO3 solution • DO NOT PIPET FROM VOLUMETRIC FLASK!! • IMMEDIATELY titrate after KI is added

  8. Procedure Notes • During the Titration: • Look for light yellow color • Add starch • Blue/Black • Titrate until clear • 1-5 drops • 3 good trials • Molarities within 5% of average

  9. Procedure Notes • Titration of Bleach • Weigh 2.000g of bleach • During the Titration: • Immediately titrate when you add KI • Look for light yellow color

  10. Procedure Notes • Add starch • Blue/Black • Titrate until clear • 1-5 drops • 3 good trials • Molarities within 5% of average • RECORD THE REPORTED MASS NaOCl FROM THE BLEACH BOTTLE!!!!!!!

  11. Waste • Solutions can go down the drain

  12. Risk assessment • Sodium Hypochlorite (Bleach) • Danger • Skin Irritant • Respiratory Irritant

  13. calculations • Molarity of KIO3 Solution: • Moles KIO3 used in titration:

  14. calculations • Moles of Na2S2O3 used in titration: • You will need to use stoichiometry • HINT look for a relationship between the two equations on page 44 • Mass Percent:

  15. Redox Equation Example Redox Equation: 1. Make sure your equation is balanced

  16. Redox equation example 2. Assign Oxidation Numbers Cu: 0 Cu : +2 S : +4 O : -8 Zn: 0 Zn : +2 S : +4 O : -8

  17. Redox equation example 3. Determine which species is oxidized and reduced Cu : +2 S : +4 O : -8 Zn: 0 Zn : +2 S : +4 O : -8 Cu: 0 Zn: 0→+2 loss of electrons Zinc is oxidized and is the reducing agent Cu: +2→0 gain electrons Copper is reduced and is the oxidizing agent

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