4$FeS_{2}$ $+_{}$ 11$O_{2}$ → $2Fe_{2}$$O_{3}$ $+_{}$ $8SO_{2}$
$2SO_{2}$ $+_{}$ $O_{2}$ → $2SO_{3}$
$SO_{3}$ $+_{}$ $H_{2}$$O_{}$ → $H_{2}$$SO_{4}$
$3H_{2}$$SO_{4}$ $+_{}$ $Fe_{2}$$O_{3}$ → $Fe_{2}$($SO_{4}$)$_{3}$ +$3H_{2}$$O_{}$
$SO_{3}$ $+ NaOH_{}$ → $NaHSO_{4}$
$NaHSO_{4}$ $+ NaOH_{}$ →$Na_{2}$$SO_{4}$ $+_{}$ $3H_{2}$$O_{}$
$Na_{2}$$SO_{4}$ $+_{}$ $BaCl_{2}$ → $2NaCl_{}$ $+_{}$ $BaSO_{4}$↓
$2NaCl_{}$ $+_{}$ $AgNO_{3}$ → $2AgCl_{}$ $+_{}$ $2NaNO_{3}$
