Write the reaction equation: a) N2 →? → (NH4) 2SO4 → NH4Cl →? → NH4Cl b) S →? → NaHSO3 → CaSO4 →? → SO3

a) 1) N2 + 3H2 -> 2NH3; 2) 2NH3 + H2SO4 (conc.) -> (NH4) 2SO4; 3) (NH4) 2SO4 + BaCl2 -> 2NH4Cl + BaSO4 (barium sulfate precipitates, the reaction goes to the end); 4) NH4Cl + NaOH -> NH3 + NaCl + H2O; 5) NH3 + HCl -> NH4Cl.
b) 1) S + O2 -> SO2 (reaction occurs when heated); 2) SO2 + NaOH (diluted) -> NaHSO3 or in another way SO2 (gr.) + NaHCO3 -> NaHSO3 + CO2; 3) 4NaHSO3 + 3CaCl2 -> Na2S + 3CaSO4 + 2NaCl + 4HCl; 4) 2CaSO4 -> 2CaO + 2SO2 + O2 (the reaction takes place at temperatures above 1450 degrees); 5) 2SO2 + O2 -> 2SO3 (when heated).