6.1 Precipitation/Double Decomposition Reactions

  Stoichiometry

In such reaction, there is no change in oxidation state of any atom. The n-factor of the salt can be calculated by multiplying the oxidation state of the cation/anion by total no. of atoms per molecule of the salt. For example

\[\mathop {BaC{l_2}}\limits_{n = 2} + \mathop {N{a_2}S{O_4}}\limits_{n = 2} \xrightarrow{{}}BaS{O_4} \downarrow + 2NaCl\]

for $BaC{l_2}$

n-factor = Oxidation state of Ba atom in $BaC{l_2}$ × number of Ba atoms in 1 molecule of $BaC{l_2}$

$ = {\text{ }}\left( { + 2} \right){\text{ }} \times {\text{ }}1{\text{ }} = {\text{ }}2$

for $N{a_2}S{O_4}$

n-factor = Oxidation state of $Na$ × number of $Na-atoms$ in 1 molecule of $N{a_2}S{O_4}$

$ = \left( { + 1} \right){\text{ }} \times {\text{ }}2{\text{ }} = {\text{ }}2$