ell T-Mobile Wi-Fi ? 6:08 AM ? CHM-01B Work Session 19A El ? ? CHEM-018 Work Ses
ID: 637800 • Letter: E
Question
ell T-Mobile Wi-Fi ? 6:08 AM ? CHM-01B Work Session 19A El ? ? CHEM-018 Work Session 19 Electrochemistry and Balancing Redox Reacions For the bollowing unbalancood net ionic reactions, add Hons and watcr,or Ol- ions and water as indicatod and as nooded Show the two half-cell neactions for cach s042 (ag) thasic solution) 10. Caloulate for the reaction beow 2 Ag(ag)Fbis) +s04- (aq)- given the following standard reduotion potentlals 2 Ag(s) +Pbs04 (s) E+0-799 11 Caloulate for the reaction be11w S cd+] (aq) + 2 Mn": (aq) + 8 H (1) 2 Mnow(aq) 5 Cd(s) given the following standard reductlon potentlals 16 H. (aq) + + E-0-40 Previous Next Dashboard Calendar ToDo Notifications InboxExplanation / Answer
Ans 9
Part a
unbalanced equation
Zn + NO3- ? Zn2+ + N2
Write oxidation numbers for each atom within brackets
Zn(0) + N(+5)O(-2)3- ? Zn(+2)2+ + N(0)2
The two half cell reactions
Oxidation reaction
O:
Zn(0) ? Zn(+2)2+
(Zn) is being oxidized from 0 to +2
Reduction reaction
R:
N(+5)O(-2)3- ? N(0)2
(N) is being reduced from +5 to 0
Balance all atoms except H & O.
O:
Zn ? Zn2+
R:
2NO3- ? N2
Balance the oxygen atoms by adding water molecules.
O:
Zn ? Zn2+
R:
2NO3- ? N2 + 6H2O
Balance the hydrogen atoms by adding protons (H+).
O:
Zn ? Zn2+
R:
2NO3- + 12H+ ? N2 + 6H2O
Balance the charge.
O:
Zn ? Zn2+ + 2e-
R:
2NO3- + 12H+ + 10e- ? N2 + 6H2O
Make electron balance
O:
Zn ? Zn2+ + 2e-
Multiply by 5
R:
2NO3- + 12H+ + 10e- ? N2 + 6H2O
Multiply by 1
O:
5Zn ? 5Zn2+ + 10e-
R:
2NO3- + 12H+ + 10e- ? N2 + 6H2O
Add half-reactions
5Zn + 2NO3- + 12H+ + 10e- ? 5Zn2+ + N2+ 10e- + 6H2O
Simplify it
5Zn + 2NO3- + 12H+ ? 5Zn2+ + N2 + 6H2O
Part b
unbalanced equation
Cl2 + S2O32- ? Cl- + SO42-
Write oxidation numbers for each atom within brackets
Cl(0)2 + S(+2)2O(-2)3 2- ? Cl(-1)- + S(+6)O(-2)4 2-
The two half cell reactions are
Oxidation reaction
O:
S(+2)2O(-2)3 2- ? S(+6)O(-2)4 2-
(S) is being oxidized
Reduction reaction
R:
Cl(0)2 ? Cl(-1)-
(Cl) is being reduced
Balance all atoms except H & O.
O:
S2O32- ? 2SO42-
R:
Cl2 ? 2Cl-
Balance the oxygen atoms by adding water molecules.
O:
S2O32- + 5H2O ? 2SO42-
R:
Cl2 ? 2Cl-
Balance the hydrogen atoms by adding protons (H+).
O:
S2O32- + 5H2O ? 2SO42- + 10H+
R:
Cl2 ? 2Cl-
in a basic medium, add OH- ion for every H+
O:
S2O32- + 5H2O + 10OH- ? 2SO42-+ 10H2O
R:
Cl2 ? 2Cl-
Balance the charge.
O:
S2O32- + 5H2O + 10OH- ? 2SO42- + 10H2O + 8e-
R:
Cl2 + 2e- ? 2Cl-
Balance electron gain
O:
S2O32- + 5H2O + 10OH- ? 2SO42- + 10H2O + 8e-
Multiply by 1
R:
Cl2 + 2e- ? 2Cl-
Multiply by 4
O:
S2O32- + 5H2O + 10OH- ? 2SO42- + 10H2O + 8e-
R:
4Cl2 + 8e- ? 8Cl-
Add the half-reactions together.
S2O32- + 4Cl2 + 5H2O + 8e- + 10OH- ?2SO42- + 8Cl- + 10H2O + 8e-
Simplify it
S2O32- + 4Cl2 + 10OH- ? 2SO42- + 8Cl- + 5H2O
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