Question

In baking powder, ${{Ca}}{\left( {{{{H}}_2}{{P}}{{{O}}_4}} \right)_2}$
A. Behaves as an acid in moist condition and decomposes ${{NaHC}}{{{O}}_3}$ to give ${{C}}{{{O}}_2}$.
B. Behaves as a base in moist condition and gives ${{{H}}_3}{{P}}{{{O}}_4}$
C. Behaves as binder
D. Behaves as filler

Answer 1

We may confuse baking soda with baking powder. We may think that both of them are the same. But they are entirely different. Baking powder is a combination of sodium bicarbonate and calcium dihydrogen phosphate.

Complete step by step answer:
As we know that the baking powder is the reason for the rising of dough or batter. It has an acid and a base for the product to rise. Baking powder completely lightens and softens the product which is known as a leavening agent. ${{Ca}}{\left( {{{{H}}_2}{{P}}{{{O}}_4}} \right)_2}$ is chemically known as calcium dihydrogen phosphate. When calcium dihydrogen phosphate reacts with the sodium bicarbonate, ${{NaHC}}{{{O}}_3}$, it produces carbon dioxide ${{C}}{{{O}}_2}$, water, calcium hydrogen phosphate ${{CaHP}}{{{O}}_4}$ and sodium hydrogen phosphate ${{N}}{{{a}}_2}{{HP}}{{{O}}_4}$. The reaction is given below:
${{Ca}}{\left( {{{{H}}_2}{{P}}{{{O}}_4}} \right)_2} + 2{{NaHC}}{{{O}}_3} \to 2{{C}}{{{O}}_2} + 2{{{H}}_2}{{O}} + {{N}}{{{a}}_2}{{HP}}{{{O}}_4} + {{CaHP}}{{{O}}_4}$
Both of these compounds will not react when the powder is dry. The reaction occurs only when we add a liquid to it. Both of them get dissolved and form a solution. Since ${{Ca}}{\left( {{{{H}}_2}{{P}}{{{O}}_4}} \right)_2}$ does not contain sodium, it is considered as the leavening acid. ${{Ca}}{\left( {{{{H}}_2}{{P}}{{{O}}_4}} \right)_2}$ has the ability to give out $60 - 70\%$ of its carbon dioxide within very short period of time of mixing.
So we can say that ${{Ca}}{\left( {{{{H}}_2}{{P}}{{{O}}_4}} \right)_2}$ acts as an acid in moist condition and decomposes ${{NaHC}}{{{O}}_3}$ to give ${{C}}{{{O}}_2}$.

Hence the correct option is A.

Additional information:
Baking powder is weaker than baking soda. The rising ability of baking soda is about three times that of baking powder. This causes an odd taste for the product. We can substitute baking powder with baking soda by adding acidic ingredients like citrus juice or cream of tartar.

Note: Baking soda and baking powder are used for different purposes which we may confuse. Baking soda is used for acidic substances or liquids. For example, citrus juice, buttermilk etc. While baking powder is used when the recipe does not have an acidic content.