Question

Să se stabilească coeficienții redox pentru următoarele reacții:
1. Cu + HNO3 → Cu(NO3)2 + NO2 + H2O
2. Cl2 + H2O →HClO + HCl
3. C + HNO3 →CO2 +NO+H2O

Answer 1

Răspuns:

$\rm1.\:\:\:\underline{\underline{Cu^0}} +H^{+1}\underline{N^{+5}}O_3^{-2}\rightarrow\underline{\underline{Cu^{+2}}}(N^{+5}O_3^{-2})_2+\underline{N^{+4}}O_2^{-2}+H_2^{+1}O^{-2}$

$\rm N^{+5}\xrightarrow{+1e^-}N^{+4}|\times2$

$\rm Cu^0\xrightarrow{-2e^-}Cu^{+2}|\times1$

Cu + 4HNO₃ → Cu(NO₃)₂ + 2NO₂ + 2H₂O

$\rm2.\:\:\:\underline{Cl_2^{0}}+H_2^{+1}O^{-2}\rightarrow H^{+1}\underline{Cl^{+1}}O^{-2}+H^{+1}\underline{Cl^{-1}}$

$\rm Cl_2^0\xrightarrow{+2e^-}2Cl^{-1}|\times2\!\!\!/\:\:1$

$\rm Cl_2^0\xrightarrow{-2e^-}2Cl^{+1}|\times2\!\!\!/\:\:1$

Cl₂ + H₂O → HClO + HCl

$\rm3.\:\:\:\underline{C^0}+H^{+1}\underline{\underline{N^{+5}}}O_3^{-2}\rightarrow\underline{C^{+4}}O_2^{-2}+\underline{\underline{N^{+2}}}O^{-2}+H_2^{+1}O^{-2}$

$\rm C^0\xrightarrow{-4e^-}C^{+4}|\times3$

$\rm N^{+5}\xrightarrow{+3e^-}N^{+2}|\times4$

3C + 4HNO₃ → 3CO₂ + 4NO + 2H₂O