Answer:
  Asahi Glass Co., Ltd answered the question regarding the chemical properties of baking soda, and Shirosaka Co., Ltd answered the question regarding the relationship between baking soda and hair.
 
 
Chemical properties of baking soda
Baking soda (sodium hydrogen carbonate or sodium bicarbonate, NaHCO₃, called Jyuso in Japanese), which is the weakest alkali among sodium compounds, has the following effects because of its properties:

1. Deodorizing
     The mechanism of deodorizing by baking soda is neutralization of acids and bases. So NaHCO₃ can remove the acid odour only. It works efficiently in fridges, garbage disposals and footwear cupboards etc.
    

2. Baking
     Carbon dioxide (CO₂) gas, generated when baking soda is broken down by heat (1), makes dough rise. You may notice that when you make pancakes because bubbles are formed as they cook.
   
   2NaHCO₃ ↔ Na₂CO₃ + CO₂+ H₂O  (1)
    

3. Polishing
     The hardness of the particle is about 2.5 on the new Mohs hardness scale, so it can remove dirt without damaging materials such as stainless steel and iron which have high values of new Mohs hardness. However, it may damage soft metals such as aluminium and copper since their values of Mohs hardness are relatively low. So please be careful when you rinse such metals with baking soda.
    

4. Washing
     Concerning the removal of dirt sticking on the surface of pots, put water in the pot, boil it and leave it overnight. The chemical reaction above (1) occurs at high temperature so that the pH of the solution in the pot is increased (pH of baking soda is around 8, pH of Na₂CO₃ is around 11). The fat in the dirt is partially saponified and the fiber in the dirt is also softened by alkali so that water can go into the gap between the stuck on dirt and surface. Then the dirt is easily removed.
     In the case of removing normal dirt, baking soda is dissociated into H⁺ and HCO₃^- in water. The HCO₃^- ion is adsorbed onto the positively charged surface of the dirt so that the dirt can be removed more easily from the surface.
    

5. Cooking beans
     Baking soda is also used to soften beans quickly. Proteins in beans are dissolved and the fibers in the beans are also softened by alkali so that water can go inside the beans more easily.
    

6. Caring for silver
     Dullness of silver (Ag), commonly called tarnish, can be removed completely using baking soda. The tarnish is silver sulfide (Ag₂S), formed when the surface of silver reacts with hydrogen sulfide (H₂S) which exists in the air in small amounts. In order to remove the tarnish, first of all, aluminium (Al) foil is put on the bottom of a pot, and baking soda and almost boiling water are put in the pot. Then tarnished silverware is placed on the aluminum foil. The difference of redox potentials between Ag and Al is so large that they form a kind of battery. Added baking soda serves as an electrolyte in this system. Therefore, the electrons move from Al to Ag so that Ag₂S releases S and the surface becomes Ag again. This process causes the tarnished silverware to become shiny again.
   *Please ventilate the air, if you do this experiment.

  Baking soda is a weak base and so it is not a powerful detergent like strong alkali which breaks down fat. However, it can remove dirt with the properties mentioned above.
 
  In order to prevent alkali from damaging your skin, use rubber gloves when you use baking soda.
 
Relationship between hair and baking soda
  First of all, baking soda is used as a dry shampoo for dogs or cats. As cleaners for pets are not covered by The Medicine Act of Health in Japan, it does not matter what compounds they contain. If something harmful happens, production is merely stopped. This can not be the case for a product applied to humans.
 
  In fact, there would be some problems if baking soda were used for shampoo/soap for humans. For example, baking soda has the ability to eliminate strong odours so that it might change the smell of perfumed materials. In addition, it might damage skin, although there are differences between individuals.
 
  Baking soda is sometimes used as one of the agents in bath powder. In fact, some hot springs in Japan contain sodium hydrogen carbonate, so this kind of hot spring is called baking soda hot spring (Jyuso-sen in Japanese) in Japan (see picture on left). It is alkaline at high temperature because of reaction (1). Baking soda hot springs containing many kinds of sodium salts, have some good effects, for example, soap works better, it softens the surface of the skin, and it removes fat and body secretions on the skin, etc. In order to imitate real hot springs, not only baking soda but also emulsifiers are added to bath powder.
 
  However, people might feel a chill after taking a baking soda spring bath since baking soda takes water out of the skin. This implies that baking soda could remove even water needed for skin and hair if it remained on the surface for a long time.
  
  As for the question about whether baking soda is good for hair, baking soda is usually used to remove hard dirt on pots or frying pans. But the protein in hair is fragile. In addition, 90% of the dirt on hair can be removed by washing with warm water only. Therefore, my conclusion is that you don't have to use baking soda to wash your hair.

  
Acknowledgement
  We thank following teachers for their careful teachings and kind suggestions in this report.

• Asahi Glass Co., Ltd

• Shirosaka Co.,Ltd
   

This article is translated by Chemistryquestion.com from the original article in Chemistryquestion.jp.  Please let us know if you find any errors.