Question

Write the balanced chemical equations for the following reactions: Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodium chloride, water, and liberates carbon dioxide.
A) $\text{ NaHC}{{\text{O}}_{\text{3}}}\text{ + 2HCl }\to \text{NaCl + 2}{{\text{H}}_{\text{2}}}\text{O + C}{{\text{O}}_{\text{2}}}\text{ }$
B) $\text{ 2NaHC}{{\text{O}}_{\text{3}}}\text{ + HCl }\to \text{ NaCl + }{{\text{H}}_{\text{2}}}\text{O + 2C}{{\text{O}}_{\text{2}}}\text{ }$
C) $\text{ NaHC}{{\text{O}}_{\text{3}}}\text{ + HCl }\to \text{ NaCl + }{{\text{H}}_{\text{2}}}\text{O + C}{{\text{O}}_{\text{2}}}\text{ }$
D) $\text{ 2NaHC}{{\text{O}}_{\text{3}}}\text{ + HCl }\to \text{ 2NaCl + }{{\text{H}}_{\text{2}}}\text{O + C}{{\text{O}}_{\text{2}}}\text{ }$

Answer 1

The balanced chemical reaction is in association with the law of conservation of mass. According to which the mass neither be created nor be destroyed in a chemical reaction. But the total mass of the atoms of the molecules on the reactant side is always equal to the mass of atoms of the molecules on the product side. The balancing is done by introducing the coefficients in front of the molecules.

Complete step by step answer:
The chemical equation is defined as the representation of the chemical reaction in terms of substance. These substances can be reactant or the product. The chemical reactions obey the law of conservation of mass. According to the law, the mass cannot be created nor be destroyed, but it can be changed from one composition to the other.
The balanced chemical reactions are the application of the law of conservation of mass. In the balanced chemical equation, the number of atoms or the number of moles of an atom of all the reactants and the product is equal on both sides of the reaction.
In other words, the number of moles of an atom on the reactant side always equals the number of moles of the same atom on the product side.
Now we have asked to balance as a chemical reaction.
The sodium hydrogen carbonate is also known as the sodium bicarbonate is treated with hydrochloric acid to give the sodium chloride, water, and liberates the carbon dioxide. The skeleton of the reaction is as follows:
$\text{ NaHC}{{\text{O}}_{\text{3}}}\text{ + HCl }\to \text{ NaCl + C}{{\text{O}}_{\text{2}}}\text{ + }{{\text{H}}_{\text{2}}}\text{O}$
Let's have a close look at the reaction. we observe that,

1. There is one sodium atom in $\text{NaHC}{{\text{O}}_{\text{3}}}\text{ }$and one in the $\text{NaCl}$(product). So , the $\text{Na}$ is balanced in the reaction.
2. There is a one chlorine atom in $\text{HCl}$(reactant) and one chlorine atom in $\text{NaCl}$. So, the chlorine is also balanced in reaction.
3. There is one C in the $\text{NaHC}{{\text{O}}_{\text{3}}}\text{ }$ and one in the$\text{C}{{\text{O}}_{\text{2}}}$, thus the carbon is balanced in the above reaction.
4. There are two hydrogen atoms on the reactant side (one from $\text{NaHC}{{\text{O}}_{\text{3}}}\text{ }$and one from$\text{HCl}$) and there are two hydrogen atoms in the water molecules${{\text{H}}_{\text{2}}}\text{O}$. Thus, here the number of hydrogen on the reactant side is equal to the number of hydrogen on the product side. Therefore, the hydrogen is balanced.
5. There are three oxygen atoms on the reactant side in $\text{NaHC}{{\text{O}}_{\text{3}}}\text{ }$ and there are two oxygen atoms in $\text{C}{{\text{O}}_{\text{2}}}$ and one oxygen in ${{\text{H}}_{\text{2}}}\text{O}$. Thus, here the number of oxygen on the reactant side is equal to the number of hydrogen on the product side that are three. Therefore, oxygen is balanced.
   Since the number of atoms on either side of the reaction is well balanced, this is the balanced chemical reaction of $\text{NaHC}{{\text{O}}_{\text{3}}}\text{ }$ with the $\text{HCl}$ to give $\text{NaCl}$, ${{\text{H}}_{\text{2}}}\text{O}$ and $\text{C}{{\text{O}}_{\text{2}}}$.

Hence, (C) is the correct option.

Note: Note that, never try to balance the equation by changing the subscript of the molecule. The subscript is unique and has characteristics of a specific molecule, which decides the number of atoms in molecules, the stability, reactivity, etc. Changing the subscript would result in the new molecules which may lead to the undesired product. Thus, always balance the reaction by considering the coefficient in front of atoms.