St. Paul

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St. Pauls Secondary School Registration No.
BCh24
??????? The Bleach File
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Introduction

• Types of Chlorine bleach
• 1. KAO Bleach
• 2. Clorox Bleach
• 3. No Frills Bleach
• 4. LibY Bleach
• Types of colour-safe bleach
• 1. Vanish in-wash stain remover (colour-safe)
• 2. KAO Liquid Wide Bleach.

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Content

• Working principles
• Chemical content
• Cleansing power towards different types of
  stains
• Possible damages to cloth
• Effect of mixing chlorine bleach and colour-safe
  bleach

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• Chemical Content and Working Principles of
  Chlorine Bleach and Colour-Safe Bleach
• Oxidizing power of the hypochlorous acid HOCl
  (aq) in chlorine bleaches
• Oxidizing power of hydrogen peroxide H2O2 (aq)
  in colour-safe bleaches.
• HOCl (aq) D ? H (aq) Cl- (aq)
  DO
• H2O2 (aq) D ? H2O (l)
  DO
• Coloured Colourless

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Investigation
Experiment 1 Aim To find out the active
ingredient in chlorine bleaches and colour safe
bleaches I )To test for ClO- in chlorine
bleaches Equation Involved OCl- (aq) Cl-
(aq) 2H (aq) ? Cl2 (g) H2O (l)
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Testing of the gas evolved after mixing chlorine
bleach with hydrochloric acid
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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.

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• Conclusion
• Active ingredient in chlorine bleaches
• hypochlorite ions
• Active ingredient in colour safe bleaches
• hydrogen peroxide

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Experiment 2 Aim To determine the concentration
of sodium hypochlorite in different brands of
household chlorine bleaches.
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To determine the concentration of sodium
hypochlorite in different brands of household
chlorine bleaches Equations involved 1) OCl-
(aq) 2I- (aq) 2H (aq) ? I2 (g) Cl- (aq)
H2O (l)
2) I2 (aq) 2S2O32- (aq) ? S4O62- (aq) 2I- (aq)
with starch added as indicator
Titrated against S2O32- (aq)
Starch added
Colour change at end point from blue to
colourless
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Conclusion
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Experiment 3 Aim To determine the concentration
of hydrogen peroxide in different brands of
colour-safe bleach
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To 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)
Colour change at the end point from colourless
to pale pink
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Price of the bleaches per number of moles of
active ingredients in chlorine bleaches and
colour-safe bleaches
Price per mole of active ingredient ()
Chlorine bleaches
Colour-safe bleaches
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• Experiment 4
• Aim
• To investigate the cleansing power and possible
  damages to cloth of different chlorine/colour-safe
  bleaches.
• Introduction
• Different kinds of cloths with different stains
  were soaked into different samples
• Changes in textures and original colour of the
  fabrics, and the degree of removal of stains
  would be considered.

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1.Curry stain Purple cotton fabric
Towel with curry stain with curry stain
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2.Dark Soy Sauce Stain Purple cotton
fabric Towel with dark with dark
soy sauce stain soy sauce stain
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3.Black Ink Stain
Purple cotton fabric with black ink stain
Towel with black ink stain
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4.Ketchup Stain
Towel with ketchup stain
Purple cotton fabric with ketchup stain
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5.Marker (Black) and Highlight Pen (Green) Stains
Purple cotton fabric with marker and highlight
pen stains
Towel with marker and highlight pen stains
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Analysis of Results 1)  Curry Stain Kao Bleach
bleached the curry stains most effectively. 2) 
Black Ink Stain Colour-safe bleach bleached the
black ink stain much better than chlorine
bleaches.
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3)  Dark Soy Sauce Stain 4)  Ketchup Stain 5) 
Marker and Highlight Pen Stains
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6.White cotton fabrics     One piece of white
cotton fabric was dipped into each of the four
different kinds of undiluted chlorine bleach for
three days.
Result The pieces of white cotton fabric turned
paler and thinner than the original sample.
LibY Bleach
No Frills Bleach
KAO Bleach
Clorox Bleach
Original sample
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7.Coloured checked fabrics     One piece of
coloured checked fabric was dipped into each of
the two different kinds of colour-safe bleach for
three days.
Result No obvious change in colour and texture.
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Conclusion
The BEST stain remover
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• Experiment 5
• Aim
• To investigate the consequences of mixing
  household chlorine bleach and colour-safe bleach
• Questions in mind ??
• What will happen if household chlorine bleach is
  mixed with colour-safe bleach?
• Will the effectiveness of the bleaching action be
  increased upon mixing?

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Chlorine bleach
Colour-safe bleach
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• High density white foam was evolved
• Heat was produced

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The beaker of foam finally overflowed.
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To collect the gas produced - by displacement
of water
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Test result The glowing splint relighted which
shows that the gas was oxygen.
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• Conclusion
• Redox reaction happened between hydrogen peroxide
  and hypochlorite ion.
• Equations involved
• OCl-(aq) H2O2(l) ? Cl-(aq) O2(g) H2O(l)
• (O.A.) (R.A.)
• An exothermic reaction
• The oxygen formed causes the formation of the
  high density white foam.

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Recommendation Never mix them together
Adding Chlorine Bleach
A lot of foam and heat are produced
Colour- safe bleach
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• Do you know how to choose between chlorine
  bleach and colour safe bleach now?

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St. Pauls Secondary School Registration No.
BCh24 Group members Ivy Yeung Vivien Chu Helen
Kwai Maggie Chow Amelia Ho Teacher Advisors Mrs.
A. Lam Miss I. Lau
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The End
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Summary

• Kao Bleach has the highest concentration of
  hypochlorite ions among the four chlorine
  bleaches
• Vanish Stain Remover has the highest
  concentration of hydrogen peroxide among the two
  colour-safe bleaches.
• The best buy of chlorine bleach is LibY Bleach
  and that of colour-safe bleach is Vanish.
• Vanish was found to be the best stain remover
  among all brands of bleaches and it does not
  affect the original colour of the fabric.
• Chlorine bleach cannot be mixed with colour-safe
  bleach when use, or else they will lose their
  bleaching power and produce excess foam.

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Discussion

• 1. Pros and cons of using the 2 different
  bleaches
• Chlorine Bleach
• Pros
• cheaper and easily available.
• can be used as disinfectant.
• turns yellowish white fabrics back to its
  original
• white colour.
• removes mildew on shower curtains, bath tubs,
  etc.
•  

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• Chlorine Bleach
• Cons
• Chlorine is a toxic chemical.
• irritates eyes and skin.
• cannot be used on coloured fabrics
• cannot be used to bleach delicate fabrics such as
  silk.
• causes water pollution.

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-  Environmental impact concerning the use of
chlorine bleach ? Excessive use of
bleaches may cause damage to the
water pipes due to its corrosive nature.
? Causes eutrophication in river and sea.
? Toxic substances may produce and will stay in
water and accumulate in the food chain.
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• H2O2 Bleach
• Pros
• H2O2 is a stronger oxidizing agent than NaOCl,
  the bleaching actions of H2O2 is faster, yet it
  does not cause any damage to fabrics.
• It is environmental friendly.
• The colour of fabrics being bleached will not
  lose its original colour.

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• H2O2 Bleach
• Cons
• Residual of H2O2 on clothes causes skin problems.
• It is more expensive than chlorine bleach.
• H2O2 is unstable and easily decomposes at high
  temperature, thus it cannot be stored for a long
  period of time.

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•  
• Further Investigation
• Possible factors affecting the bleaching power of
  the bleaches
• Temperature
• pH values

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How does bleach remove colour in organic
compounds? Colour in organic materials is the
result of light absorption by certain chemical
configurations called chromophores in molecules.
CC and CO bonds are examples of chromophores. A
chromophore, e.g. CC and CO, is a part of a
molecule that is able to absorb UV light or
visible light and producing colour in organic
compounds. Oxidizing bleaches break up these
double bonds Reducing bleaches convert
double bonds to single bonds
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Prices of different bleaches Kao Bleach
14.9 per 600ml Clorox Bleach 7.9 per
710ml No Frills 9.9 per 2000ml
LibY Bleach 6.2 per 1500ml
Prices of different colour-safe bleaches Vanish
Stain Remover 19.9 per 1kg Kao Liquid Wide
Bleach 17.9 per 1000ml
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E(V) Half
equation 0.68 O2 2H 2e- ?
H2O2 0.89 ClO- H2O 2e- ? Cl-
2OH- 1.77 H2O2 2H 2e- ? 2H2O2