Question

C10H12O4S(s) + O2(g)  CO2(g) + SO2(g) + H2O(g)

Answer 1

Answer: The coefficient for $O_2(g)$ is 12.

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

$C_{10}H_{12}O_4S(s)+12O_2(g)\rightarrow 10CO_2(g)+SO_2(g)+6H_2O$

Thus in the reactants, there are 12 molecules of oxygen in balanced chemical equation. Thus the coefficient for $O_2(g)$ is 12.