Question

The balanced chemical equation for the thermal decomposition of ferrous sulphate crystals is :
a.) $6FeS{O_4}(s)\xrightarrow{{heat}}3F{e_2}{O_3}(s) + S{O_2}(g) + 4S{O_3}(g)$
b.) $3FeS{O_4}(s)\xrightarrow{{heat}}F{e_3}{O_4}(s) + S{O_2}(g) + S{O_3}(g)$
c.) $2FeS{O_4}(s)\xrightarrow{{heat}}F{e_2}{O_3}(s) + S{O_2}(g) + S{O_3}(g)$
d.) $FeS{O_4}(s)\xrightarrow{{heat}}F{e_2}{O_3}(s) + S{O_2}(g) + S{O_3}(g)$

Answer 1

A balanced chemical equation is the one in which the number of atoms for each element in the reaction and total charge is same for both reactants and products. Count the number of atoms of reactants and products in each option and see which one is the balanced.

Complete answer:
A balanced chemical equation is the one in which the number of atoms for each element in the reaction and total charge is the same for both reactants and products.
Let us count the number of atoms of reactants and products in each option and see which one is the balanced.
The first option is -
$6FeS{O_4}(s)\xrightarrow{{heat}}3F{e_2}{O_3}(s) + S{O_2}(g) + 4S{O_3}(g)$

Element	Reactant	Product
Fe	6	6
S	6	5
O	24	23

From the table we see that S and O have different numbers of atoms on both sides.
So, this is not the correct option.
The second option is -
$3FeS{O_4}(s)\xrightarrow{{heat}}F{e_3}{O_4}(s) + S{O_2}(g) + S{O_3}(g)$

Element	Reactant	Product
Fe	3	3
S	3	2
O	12	9

From the table we see that S and O have different numbers of atoms on both sides.
So, this is not the correct option.
The third option is -
$2FeS{O_4}(s)\xrightarrow{{heat}}F{e_2}{O_3}(s) + S{O_2}(g) + S{O_3}(g)$

Element	Reactant	Product
Fe	2	2
S	2	2
O	8	8

From the table we see that all atoms are the same on both sides.
So, this can be the correct option.
The fourth option is -
$FeS{O_4}(s)\xrightarrow{{heat}}F{e_2}{O_3}(s) + S{O_2}(g) + S{O_3}(g)$

Element	Reactant	Product
Fe	1	2
S	1	2
O	4	8

From the table we see that Fe, S and O have different numbers of atoms on both sides.
So, this is not the correct option.

Thus, the option c.) is the correct answer.

Note:
It must be noted that a balanced equation explains the accurate number of atoms of an element required for a chemical reaction. If the equation is balanced, we can know the limiting reagent.