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1、St. Pauls Secondary SchoolSt. Pauls Secondary SchoolRegistration No. :BCh24 開心漂白大發現開心漂白大發現The Bleach FileThe Bleach FileIntroductionIntroductionTypes of Chlorine bleach:1.KAO Bleach 2.Clorox Bleach3.No Frills Bleach 4.LibY Bleach Types of colour-safe bleach1.Vanish in-wash stain remover (colour-safe
2、) 2.KAO Liquid Wide Bleach. Working principlesChemical contentCleansing power towards different types of stains Possible damages to clothEffect of mixing chlorine bleach and colour-safe bleachContent Content Chemical Content and Working PrincipleChemical Content and Working Principles s of of Chlori
3、ne Bleach andChlorine Bleach and Colour Colour-S-Safe Bleachafe Bleach: :Oxidizing power of the hypochlorous acid HOCl (aq) in chlorine bleachesOxidizing power of hydrogen peroxide H2O2 (aq) in colour-safe bleaches. HOCl (aq) + D H+ (aq) + Cl- (aq) + DOH2O2 (aq) + D H2O (l) + DOColoured Colourless E
4、xperiment 1Aim: To find out the active ingredient in chlorine bleaches and colour safe bleachesI )To test for ClO- in chlorine bleaches: Equation Involved: OCl- (aq) + Cl- (aq) + 2H+ (aq) Cl2 (g) + H2O (l)InvestigationInvestigationTesting of the gas evolved after mixing chlorine bleach with hydrochl
5、oric acid(II) To test for H2O2 in colour safe bleaches: Equation involved: 2H2O2 (aq) O2 (g) + 2H2O(l) Results:A gas was evolved The glowing splint relighted, which suggests that the gas is oxygen.Conclusion:Active ingredients in chlorine bleaches hypochlorite ionsActive ingredient in colour safe bl
6、eaches hydrogen peroxideExperiment 2Aim: To determine the concentration of sodium hypochlorite in different brands of household chlorine bleaches.To determine the concentration of sodium hypochlorite in different brands of household chlorine bleaches.Equations involved: 1) OCl- (aq) + 2I- (aq) + 2H+
7、 (aq) I2 (g) + Cl- (aq) + H2O (l)2) I2 (aq) + 2S2O32- (aq) S4O62- (aq) + 2I- (aq)Titrated against S2O32- (aq) S2O32- (aq)Colour change at end point: from blue to colourlesswith starch added as indicatorStarch addedDiluted chlorine bleach, KI and H2SO4 Brands of chlorine bleachMolarity of NaOCl Kao B
8、leach 2.2M Clorox Bleach 2.12MNo Frills Bleach 1.99MLibY Bleach 1.88MGreatest molarity of NaOClConclusion:Brands of bleachPrice of bleach per mole of NaOCl Kao Bleach $11.3 Clorox Bleach $6.21No Frills Bleach $2.49LibY Bleach $2.20Brands of chlorine bleachPrice per mole of NaOCl ($)Best buyExperimen
9、t 3Aim: To determine the concentration of hydrogen peroxide in different brands of colour-safe bleachTo determine the concentration of hydrogen peroxide in different brands of colour-safe bleach.Equation involved: 6H+(aq) + 2MnO4- (aq) + 5H2O2 (l) 5O2 (g) + 2Mn2+ (aq) + 8H2O (l)MnO4- (aq)Colour chan
10、ge at end point: from colourless to pale pink Diluted colour-safe bleachBrands of bleachMolarity of NaOCl Price of bleach per mole of NaOCl Vanish Stain Remover 1.90M$10.6Kao Liquid Wide Bleach 1.38M$13.0Highest molarity of H2O2Best BuyBrands of colour safe bleachPrice per mole of H2O2 ($)Price of t
11、he bleaches per number of moles of active ingredients in chlorine bleaches and colour safe bleachesPrice per mole of active ingredient ($)Chlorine bleachesColour safe bleachesmore expensiveExperiment 4Aim: To investigate the cleansing power and possible damages to cloth of different chlorine/colour-
12、 safe bleaches.Introduction: Different kinds of cloths with different stains were soaked into different samplesChanges in textures and original colour of the fabrics, and the degree of removal of stains would be considered. 1.Curry stain Purple cotton fabric Towel with curry stain with curry stain2.
13、Dark Soy Sauce Stain Purple cotton fabric Towel with dark with dark soy sauce stain soy sauce stain 3.Black Ink Stain Purple cotton fabric with black ink stain Towel with black ink stain 4.Ketchup Stain Towel with ketchup stain Purple cotton fabric with ketchup stain 5.Marker (Black) and Highlight P
14、en (Green) Stains Purple cotton fabric with marker and highlight pen stains Towel with marker and highlight pen stains Analysis of Results:1) Curry StainKao bleached the curry stains most effectively.2) Black Ink StainAll the results were unsatisfactory.Colour-safe bleach bleached the black ink stai
15、n much better than chlorine bleaches. 3) Dark Soy Sauce Stain4) Ketchup Stain5) Marker and Highlight Pen StainsSimilar performance on6.White cotton fabrics One piece of white cotton fabric was dipped into each of the four different kinds of undiluted chlorine bleach for four days.Result:The pieces of white cotton fabric turned paler and thinner than the original sample. KAO BleachLibY BleachNo Frills BleachOriginal sampleClorox Bleach7.Coloured checked fabrics One piece of coloured checked fabric was dipped into each of the two different
