Câu 2:
$H_2S+ \frac{3}{2} O_{2_{\text{dư}}} \buildrel{{t^o}}\over\longrightarrow SO_2+ H_2O$
$2H_2S+ O_{2_{\text{thiếu}}} \buildrel{{t^o}}\over\longrightarrow S+ 2H_2O$
$2NaOH+ H_2S \rightarrow Na_2S+ 2H_2O$
$NaOH+ H_2S \rightarrow NaHS+ H_2O$
$H_2S+ 4Cl_2+ 4H_2O \rightarrow 8HCl+ H_2SO_4$