Respuesta :
Answer:
a) 12H+ + 6Zn + 2NO3 → 6Zn2+ + N2 + 6H2O
b) 12H2O + 9Zn + 2NO3 → 9Zn2+ + 2NH3 + 18OH-
c) 4H+ + 2CuS + NO3 → 2Cu2+ + 2S + NO + 2H2O
d) 7O2 + 4NH3 → 4NO2 + 6H2O
e) 13Cl2 + 26OH- + 10OH + → 6ClO3- + 18H2O + 20Cl-
f) 5H2O2 + 2MnO4- + 6H+ → 5O2 + 2Mn2+ + 8H2O
g) 2NO2 + 2OH- → NO3- + NO2- + H2O
h) 2I- + 2Fe3+ → I2 + 2Fe2+
Explanation:
a) oxidation states :
⇒ Zn: 0 → 2+ : lose 2e-
⇒ N : +6 → 0 : win 6e-
half reaction:
⇒ ( 1 ) Zn → Zn2+ + 2e-
⇒ ( 2 ) 2NO3 + 12H+ 12e- → N2 + 6H2O...........The O are balanced with H2O and the H with H +, then balanced the charges with e-.
( 1 ) * 6:
⇒ ( 7 ) 6Zn → 6Zn2+ + 12e-
( 7 ) + ( 2 ):
⇒ 12H+ + 6Zn + 2NO3 → 6Zn2+ + N2 + 6H2O
6 - Zn - 6
2 - N - 2
6 - O - 6
12 - H - 12
b) oxidation states:
⇒ Zn: 0 → 2+ ≡ 2e-
⇒ N: +3 → -3 ≡ 6e-
half reaction:
( 1 ) Zn → Zn2+ + 2e-
(2 ) 9H2O + 9e- + NO3 → NH3 + 3H2O + 9OH-......each H + ion present in the equation is added a respective OH- ion to each side of the equation, and the combination of OH- and H + ions found on the same side of the equation is replaced with a water molecule.
∴ ( 1 ) * 9 and ( 2 ) * 2 and then i add them:
⇒ 18H2O + 9Zn + 2NO3 → 9Zn2+ + 2NH3 + 6H2O + 18OH-
9 - Zn - 9
2 - N - 2
24 - O - 24
36 - H - 36
c) oxidation states:
∴ S: -2 → 0 ≡ 2e-
∴ N: +6 → +2 ≡ 4e-
half reaction:
( 1 ) CuS → Cu2+ + S + 2e-
( 2 ) NO3 + H2O + 4H+ + 4e- → NO + 3H2O
∴( ( 1 ) * 2 ) + ( 2 ):
⇒ 4H+ + 2CuS + NO3 → 2Cu2+ + 2S + NO + 2H2O
2 - Cu - 2
1 - N - 1
2 - S - 2
3 - O - 3
4 - H - 4
d) oxidation states:
∴ O: 0 → -2 ≡ 2e-
∴ N: -3 → +4 ≡ 7e-
half reaction:
( 1 ) O2 + 4H+ + 4e- → 2H2O
( 2 ) NH3 + 2H2O → NO2 + 7H+ + 7e-
∴ ( 1 ) * 7 and ( 2 ) * 4 and then i add them:
⇒ 7O2 + 4NH3 + 8H2O → 4NO2 + 14H2O
⇒ 7O2 + 4NH3 → 4NO2 + 6H2O
4 - N - 4
14 - O - 14
12 - H - 12
e) oxidation states:
∴ Cl: 0 → -1 ≡ 1e-
∴ Cl: 0 → +5 ≡ 5e-
∴ O: -1 → -2 ≡ 1e-
half reaction:
( 1 ) Cl2 + 6H2O → 2ClO3- + 12H+
( 2 ) Cl2 + OH + H+ → Cl- + H2O
in base:
( 1 ) Cl2 + 6H2O + 12OH- → 2ClO3- + 12H2O
( 2 ) Cl2 + OH + H2O → 2Cl- + H2O + OH-
the charge are balanced:
( 1 ) Cl2 + 6H2O + 12OH- → 2ClO3- + 12H2O + 10e-
( 2 ) Cl2 + OH + H2O + 3e- → 2Cl- + H2O + OH-
∴ ( 1 ) * 3 and ( 2 ) * 10, then i add them:
⇒ 13Cl2 + 26OH- + 10OH + → 6ClO3- + 18H2O + 20Cl-
26 - Cl - 26
36 - O - 36
36 - H - 36
f) oxidation states:
∴ O: -1 → 0 ≡ 1e-
∴ O: -2 → 0 ≡ 2e-
∴ Mn: +7 → +2 ≡ 5e-
half reaction:
( 1 ) H2O2 → O2 + 2H+ + 2e-
( 2 ) MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
∴ ( 1 ) * 5 and ( 2 ) * 2, then i add them:
⇒5H2O2 + 2MnO4- + 6H+ → 5O2 + 2Mn2+ + 8H2O
2 - Mn - 2
18 - O - 18
16 - H - 16
g) oxidation states:
∴ N: +4 → +5 ≡ 1e-
∴ N: +4 → +3 ≡ 1e-
half reaction:
( 1 ) NO2 + H2O + 2OH- → NO3- + 2H+
( 2 ) NO2 → NO2-
⇒ ( 1 ) NO2 + H2O + 2OH- → NO3- + 2H2O + 1e-
⇒ ( 2 ) NO2 + 1e- → NO2-
( 1 ) + ( 2 ):
⇒ 2NO2 + 2OH- → NO3- + NO2- + H2O
2 - N - 2
6 - O - 6
2 - H - 2
h) oxidation states:
∴ Fe: +3 → +2 ≡ 1e-
∴ I: -1 → 0 ≡ 1e-
half reaction:
( 1 ) 2I- → I2 + 2e-
( 2 ) Fe3+ +1e- → Fe2+
∴ (( 2 ) * 2 ) + ( 1 ):
⇒ 2I- + 2Fe3+ → I2 + 2Fe2+
2- I - 2
2 - Fe - 2
