1. So-called optical bleaches, also known as optical whitening/brightening agents, are not really bleaches, but fluorescent dyes that convert invisible ultra-violet light of very short wavelength into visible blue or blue-green light with longer wavelength. Whites that are bluer in cast are often perceived to be ‘purer’, thus fluorescent dyes have the potential for making fabrics and other materials appear brighter to the eye.

   Blancophor R.
   Blancophor R., an optical brightener, is able to convert ultra-violet light into blue light and therefore reduce the yellowing effect in fabrics.

2. A bleaching detector is actually an acid solution of ortno-tolidine used in detecting the presence of chlorine bleach. It is very sensitive and gives an approximation of the amount of bleach present by the intensity of yellow colour produced.

   A bleach indicator is actually potassium iodide KI, used by method of titration to determine the % of available chlorine in bleach.

3. Do not mix oxidising agents and reducing agents together because the results may be Disastrous!!

In the local market

Liquid household bleaches are commonly based on NaOCl as the active ingredient at a concentration of 5-5.5%. Industrial strength versions are often several times more concentrated.

Popular brands found in the markets are Clorox, Kao’s, NTUC and Tops, just to name a few. Right now, let’s investigate these brands of bleaches…

Such a warning exists:

• "Not for internal use."

• " If swallow, drink milk and seek for medical help immediately."

Now, why do we need to drink milk if we happen to swallow bleach? (It shouldn’t happen!)?
As a matter of fact, NaOCl has a pH value of 11.2, which makes it a strong base. Milk, on the other hand, is an acid of pH 6. If an alkaline solution of NaOCl is taken into the body, an acid (milk) will be the next best substance to be consumed to counteract the effect of NaOCl in the body through neutralisation.

• "Instruction: Do Not mix bleach with an acidic cleaner!!!"
  
  Why?
  The answer is the same as before.

• Instruction: Add bleach in warm water to remove stubborn stains.
  
  Why do we need to use warm water?
  An increase in temperature increases the average kinetic energy of the molecules. This results in an increase in the frequency of collisions between the molecules. Therefore fraction of molecules having energy³ activation energy is significantly increased. Hence number of effective collisions increase leading to an increase in reaction rate.

According to a label on a bottle of bleach, bleaching is divided into two types:

Solid or Liquid?

Would you prefer powdered or liquefied bleach if using powdered bleach requires ½ cups per 2 liters of water for clothes which have turned yellow, while using liquefied bleach requires ¾ cups per 30 liters?
Well, you decide.

In conclusion, many manufacturers claim that their bleaching products are more superior to others, by introducing ‘multi-purpose’ bleaches that boast cleaner and whiter results on stained fabrics than normal detergents. Some bleaches are even able to disinfect anything from toilet bowls to diapers. Some also provide ‘money-back guaranteed’, if their products do not meet the expectations of their customers. Other manufacturers produce bleaches with popular fragrances, such as the lemon scent or specific bleaches for precise usage. Well, are they truthful claims? It’s all up to us to find out for ourselves.

Bilography

• Encarta’95
• "Chemistry" by Mcmurry Fay
• "Chemistry in Action" by Michael Freemantle
• "Chemistry and our Changing World" by Alan Sherman and Sharon J.Sherman

Examples of Bleaching Agents