Question

Balance the following equation:

Answer 1

Answer: a) $2K_2CrO_4+3Na_2SO_3+10HCl\rightarrow 4KCl+3Na_2SO_4+2CrCl_3+5H_2O$

b) 1 mole of $SO_2$ is produced.

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.

The skeletal equation is:

$K_2CrO_4+Na_2SO_3+HCl\rightarrow KCl+Na_2SO_4+CrCl_3 +H_2O$

The balanced equation will be:

$2K_2CrO_4+3Na_2SO_3+10HCl\rightarrow 4KCl+3Na_2SO_4+2CrCl_3+5H_2O$

Thus the coefficients are 2, 3 , 10 , 4 , 3 , 2 and 5.

b) Oxidation: $2I-^-\rightarrow I_2+2e-^-$

Reduction: $SO_4^{2-}+2e^-+4H^+\rightarrow SO_2+2H_2O$

Net reaction:  $2I-^-+SO_4^{2-}+4H^+\rightarrow I_2+SO_2+2H_2O$

When 1 mole of $I_2$ is produced, 1 mole of $SO_2$ is produced.