BAKING SODA

Since early times, baking soda has been used as baking powder, abrasive, deodorant, cleaner and so on. Does anyone ever wonder why baking soda has so many functions?

Chemical properties of baking soda
Baking soda (sodium hydrogen carbonate or sodium bicarbonate, NaHCO₃), which is the weakest alkali among sodium compounds, has the following effects because of its properties:

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.

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)

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.

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 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.

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.

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.

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 our skin, always remember to use rubber gloves when using baking soda.