Răspuns:
a. 2HNO3 +3H2S=>3S+2NO+,4H2O
S-² - 6 e- => S⁴ (oxidare agent reducator)
2 N⁵ + 6 e- =>2 N² (reduction)
b.
4HNO3 +3C=> 3CO2+4N4O+2H2O
3 C⁰ - 12 e- =>3 C⁴(oxidare agent redactor
4 N⁵ + 12 e- => 4 N ² (reducere agent oxidant)
C.
SO2 +2CuCl2 +2H2O =>2CuCl + H2SO4 +2HCl
2 Cu² + 2 e- => 2 Cu¹ ( reducere agent oxidant )
S⁴ - 2 e- =>S⁶ (oxidareagent reducator )
