1/
$25Fe+96HNO_{3} \to 25Fe(NO_{3})_{3}+9NO+6N_{2}O+48H_{2}O$
Ta có: $\frac{nNO}{nN_{2}O}=\frac{3}{2}$
$Fe^{0} \to Fe^{+3} +3e$ .25
$7N^{+5} +25e \to N^{+2}.3 +N_{2}^{+1}.2$ . 3
2/
$14Al+30H_{2}SO_{4} \to 7Al_{2}(SO_{4})_{3}+3SO_{2}+6S+30H_{2}O$
Ta có $\frac{nSO_{2}}{nS}=\frac{1}{2}$
$2Al^{0} \to Al_{2}^{+3} +6e$ .7
$3S^{+6} +14e \to S^{+4} +2S^{0}$ .3
3/
$22Mg+54HNO_{3} \to 22Mg(NO_{3})_{2} +2N_{2}+3NH_{4}NO_{3}+21H_{2}O$
Ta có $\frac{nN_{2}}{nNH_{4}NO_{3}}=\frac{2}{3}$
$Mg^{0} \to Mg^{+2} +2e$ .22
$7N^{+5} +44e \to 2N_{2}^{0} +3N^{-3}$ .1