Question

Balance the following chemical reactions:
A. $HN{O_3} + Ca{(OH)_2} \to Ca{\left( {N{O_3}} \right)_2} + {H_2}O$
B. $NaCl + AgN{O_3} \to AgCl + NaN{O_3}$
C. $BaC{l_2} + {H_2}S{O_4} \to BaS{O_4} + HCl$

Answer 1

Hint: We need to know what constitutes a chemical reaction and the rules for balancing them. The reaction between atoms or molecules to produce a new compound or molecule is known as a chemical reaction. The atoms or molecules or compounds taking part in a reaction are known as reactants and the final converted substances are known as the products. They are separated by a forward arrow $\left( \to \right)$ with the reactants on the left-hand side and products on the right-hand side of the arrow. The number of reactants or products are represented by coefficients which are placed on the left of each reactant or product.

Complete step by step answer:
Now that we know what are reactants, products and coefficients, we can define the rules needed to balance a chemical reaction. The most important rule to balance an non-ionic reaction is :
The number of atoms of each element must be the same on each side of the equation,i.e. the number of atoms taking part in the reaction should be equal to the number of atoms in the products. This is due to the law of conservation of masses as the mass of any one element at the beginning of a reaction will be equal to the mass of that element at the end of the reaction. These numbers of atoms are represented by the coefficients.
Let us take the example of splitting up of a water molecule $\left( {{H_2}O} \right)$ to yield molecular hydrogen and oxygen:
${H_2}O \to {H_2} + {O_2}$
This equation above is said to be unbalanced as the number of atoms of hydrogen and oxygen are unequal on both sides of the reaction.
The balanced reaction is as follows:
$2{H_2}O \to 2{H_2} + {O_2}$
The coefficients added in front of ${H_2}O$ and ${H_2}$ balances the reaction as the number of atoms of hydrogen and oxygen are equal on both sides of the reaction.
We can now balance the given reactions in a similar manner:
$HN{O_3} + Ca{(OH)_2} \to Ca{\left( {N{O_3}} \right)_2} + {H_2}O$
In order to balance the above reaction, we can put 2 before, HNO3 in the left hand side and put 2 before the water molecule in the right hand side.
We can write the balanced chemical reaction as,
$2HN{O_3} + Ca{(OH)_2} \to Ca{\left( {N{O_3}} \right)_2} + 2{H_2}O$
$NaCl + AgN{O_3} \to AgCl + NaN{O_3}$
This chemical reaction is already balanced as the number of atoms of each element is the same on either side of the reaction.
Now we can discuss about the option c as,
$BaC{l_2} + {H_2}S{O_4} \to BaS{O_4} + HCl$
In order to balance the above equation, we can put 2 before the HCl in the left hand side.
We can write the balanced chemical reaction as,
$BaC{l_2} + {H_2}S{O_4} \to BaS{O_4} + 2HCl$

Note:
It must be noted that for those elements or compounds for which there is no coefficient placed, the number of atoms of atoms is equal to its subscript. If there is a coefficient present, the subscript is multiplied with the coefficient to get the number of atoms. Also, the net charge must be the same on each side of the equation once it has been balanced. This stands true only in case of ionic reactions.