Question

Balance the following chemical equations:
A.$FeS + HCl \to FeC{l_2} + {H_2}S$
B.$N{a_2}C{O_3} + HCl \to NaCl + {H_2}O + C{O_2}$

Answer 1

Hint: We know that a balanced chemical equation has the same number of atoms for each element that occurs in the chemical reaction. We have to calculate the number of atoms for a given element by multiplying the coefficient of any formula containing that element by the subscript of the element present in the formula. If we observe an element that is seen more than time in one formula on a given side of the equation, we have to compute the number of atoms and then add them together.

Complete step by step solution:
The given chemical equation is,
$FeS + HCl \to FeC{l_2} + {H_2}S$
We have to remember that the reaction of iron (II) sulfide with hydrochloric acid is an example of double displacement reaction.
When an iron (II) sulfide reacts with hydrochloric acid to form products iron (II) chloride and hydrogen sulfide. The chemical reaction is,
$FeS + HCl \to FeC{l_2} + {H_2}S$(Unbalanced)
Place a coefficient 2 in front of $HCl$ on the reactant side to balance the chlorine and hydrogen atoms.
All the other atoms are balanced.
We can write the balanced equation as,
$FeS + 2HCl \to FeC{l_2} + {H_2}S$(Balanced)
Each side comprises $1Fe's,2H's,2Cl's,1S's$ atoms.
The given chemical equation is,
$N{a_2}C{O_3} + HCl \to NaCl + {H_2}O + C{O_2}$
When the reaction of sodium carbonate with hydrochloric acid forms sodium chloride and carbonic acid. Due to the unstable nature of carbonic acid, it decomposes into carbon dioxide and water.
We have to remember that the sodium carbonate in reaction with hydrochloric acid forms product sodium chloride, water and carbon dioxide. The chemical reaction is,
$N{a_2}C{O_3} + HCl \to NaCl + {H_2}O + C{O_2}$(Unbalanced)
Place a coefficient 2 in front of $HCl$ on the reactant side to balance the chlorine and hydrogen atoms.
Place a coefficient 2 in front of $NaCl$ on the reactant side to balance the sodium atoms.
All the other atoms are balanced.
We can write the balanced chemical equation as,
$N{a_2}C{O_3} + 2HCl \to 2NaCl + {H_2}O + C{O_2}$(Balanced)
Each side comprises $2Na's,2H's,2Cl's,1C's,3O's$ atoms.

Note: As we know that based on the law of conservation of mass, matter could not be created or destroyed. So, the mass of the products in a chemical reaction is the same as the mass of the reactants. The aim of balancing chemical equations is to contain the equal number of each kind of element on each side of a chemical equation. Balancing chemical equations also helps to obtain the stoichiometric relationship between the substances/elements/compounds.