Question

The baking soda formula is:
(A) \[{{K}_{2}}C{{O}_{3}}\]
(B) \[NaHC{{O}_{3}}\]
(C) both a and b
(D) none of these

Answer 1

Hint: Baking soda releases carbon dioxide when the medium is acidic and is, therefore, used in making cakes, cookies, breads, biscuits and other baked products. Release of carbon dioxide expands the dough used for making baked products which is why they are porous and palatable.

Complete answer:
Sodium bicarbonate or sodium hydrogen carbonate, \[NaHC{{O}_{3}}\] is commonly referred to as baking soda.\[NaHC{{O}_{3}}\] acts as baking soda because it reacts with the acid present in the medium to give sodium salt and carbonic acid (\[{{H}_{2}}O+C{{O}_{2}}\text{ or }{{H}_{2}}C{{O}_{3}}\]), which further decomposes to give water and carbon dioxide. The chemical reaction involved is given as:

$NaHC{{O}_{3}}+{{H}^{+}}\to N{{a}^{+}}+{{H}_{2}}C{{O}_{3}}$

${{H}_{2}}C{{O}_{3}}\to {{H}_{2}}O+C{{O}_{2}}\uparrow$

Potassium carbonate, \[{{K}_{2}}C{{O}_{3}}\] is more basic than \[NaHC{{O}_{3}}\] since it has no acidic hydrogen like \[NaHC{{O}_{3}}\] does. So, when \[{{K}_{2}}C{{O}_{3}}\] reacts with an acid \[C{{O}_{2}}\] is released vigorously along with the formation of potassium salt and water. So, it is not usually used in baking. Therefore, the chemical formula for the most commonly used substance as baking soda is \[NaHC{{O}_{3}}\].

Therefore, the correct option is (B).

Additional Information At pH below 5, baking soda is completely dissociated into \[C{{O}_{2}}\] and pH above 7-8, no \[C{{O}_{2}}\] is left in the dough prepared for baking. \[NaHC{{O}_{3}}\] is a white salt formed by sodium and bicarbonate ion and is soluble in water. Baking is a good source of sodium for the human body. \[{{K}_{2}}C{{O}_{3}}\] is a colourless crystal and has a salty taste.

Note: Physical appearance of potassium carbonate resembles that of sodium bicarbonate but their chemical properties are completely different. Note that sodium carbonate, \[N{{a}_{2}}C{{O}_{3}}\] is known as washing soda and sodium bicarbonate, \[NaHC{{O}_{3}}\] is baking soda.