a) Ta có: \(\overset{0}{C}\rightarrow\overset{+4}{C}+4e\) (Nhân với 3)
\(2\overset{+5}{N}+\overset{0}{S}+12e\rightarrow\overset{0}{N_2}+\overset{-2}{S}\) (Nhân với 1)
\(\Rightarrow\) PTHH: \(2KNO_3+S+3C\rightarrow K_2S+N_2+3CO_2\)
b) Ta có: \(\overset{0}{Cl_2}+2e\rightarrow2\overset{-1}{Cl}\)
\(\overset{0}{Cl_2}\rightarrow2\overset{+1}{Cl}+2e\)
\(\Rightarrow\) PTHH: \(2NaOH+Cl_2\rightarrow NaCl+NaClO+H_2O\)