Question

- Why do $CaC{{O}_{3}}+C{{O}_{2}}+{{H}_{2}}O$ form $Ca{{(HC{{O}_{3}})}_{2}}$ ?

Answer 1

Calcium carbonate, a inorganic compound, insoluble in water and forms ions and when treated with carbon dioxide forms ${{H}_{2}}C{{O}_{3}}$ which also dissociates into ions, the carbonate ion gets protonated and its concentration decreases and it shifts the position of equilibrium. Now you can easily answer the given statement.
Complete step by step answer:
First, we should know what a chemical reaction is. The reaction in which the reactants react with each other to form two or more products is known as the chemical reaction. The reactants are written on the left hand side and the products are written on the right-hand side and there is an arrow from left to the right symbolizing a complete chemical reaction.
Example: consider the general reaction as:
$A+B\to C+D$
Here, A and B are the reactants and C and D are the products and the arrow indicates the direction in which the chemical reaction occurs.
Now considering the statement as;
When calcium carbonate is made to react with carbon dioxide in the presence of water, it results in the formation of calcium bicarbonate. The reaction is supposed to take place as;-
It is so because calcium carbonate is insoluble in water and dissociates into ions as;-
$CaC{{O}_{3}}\rightleftharpoons C{{a}^{2+}}+{CO_{3}}^{2-}$ (1)
When it is treated with carbon dioxide, it results in the formation of ${{H}_{2}}C{{O}_{3}}$ which also dissociates into two ions.
Thus, the solution now consists of three ions i.e. $HCO_{3}^{-},{{H}^{+}}\text{ and CO}_{3}^{2-}$.
Now, the carbonate ions in equation (1), gets protonated by the proton of the ${{H}_{2}}C{{O}_{3}}$, therefore the concentration of the carbonate ions in the solution decreases and the position of the equilibrium gets shifted in the forward direction resulting in the more and mores dissociation of the calcium carbonate and thus, that’s why when calcium carbonate is reacted with carbon dioxide and water, it results in the formation of calcium bicarbonate.
Note: Always keep in mind that at the point of equilibrium the concentration of the reactants and the products are always equal and the rate of forward reaction is equal to the rate of the backward reaction and vice-versa.