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Balancing Redox Equations - General Chemistry II | CHEM 1120, Assignments of Chemistry

Roane State Community CollegeChemistry

Material Type: Assignment; Class: General Chemistry II; Subject: Chemistry; University: Roane State Community College; Term: Unknown 1989;

Typology: Assignments

Pre 2010

Uploaded on 08/19/2009

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Page 128
Balancing Redox Reactions
Balance the following reactions using the Half-Reaction
technique. Refer to the instructions and the example of the
permanganate-oxalate reaction.
1) Fe3+ +I
-โ†’Fe2+ +I
2
1x 2I
-โ†’I2+2e
-
2x Fe
3+ +1e
-โ†’Fe2+
2Fe3+ +2I
-โ†’2Fe2+ +I
2
2) Cl2+Br
-โ†’Br2+Cl
-
1 x 2Br-โ†’Br2+2e
-
1x Cl
2+2e
-โ†’2Cl-
Cl2+ 2Br-โ†’Br2+ 2Cl-
3) Zn + Hg22+ โ†’Zn2+ +Hg
1x Zn โ†’Zn2+ +2e
-
1x 2e
-+Hg
22+ โ†’2Hg
Zn + Hg22+ โ†’Zn2+ + 2Hg
4) I-+ ClO4-+H
+โ†’I2+ ClO3-+H
2O
1x 2e
-+ ClO4-+2H
+โ†’ClO3-+H
2O
1x 2I
-โ†’I2+2e
-
2I-+ ClO4-+2H
+โ†’I2+ ClO3-+H
2O
5) Cu + NO3-+H
+โ†’Cu2+ +NO
2-+H
2O
1x Cu โ†’Cu2+ +2e
-
1x 2e
-+NO
3-+2H
+โ†’NO2-+H
2O
Cu + NO3-+2H
+โ†’Cu2+ +NO
2-+H
2O
6) H2S+ Cr
2O72- +H
+โ†’Cr3+ +S
8+H
2O
8x 6e
-+Cr
2O72- + 14H+โ†’2Cr3+ +7H
2O
3x 8H
2Sโ†’S8+ 16H++ 16e-
24H2S + 8Cr2O72- + 64H+โ†’16Cr3+ +3S
8+ 56H2O
7) MnO4-+C
2O42-+OH
-โ†’MnO2+CO
32- +H
2O
2 x MnO4-+3e
-+2H
2Oโ†’MnO2+ 4OH-
3x C
2O42- + 4OH-โ†’2CO32- +2H
2O+ 2e
-
2MnO4-+3C
2O42- + 4OH-โ†’2MnO2+ 6CO32- +2H
2O
pf3

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Download Balancing Redox Equations - General Chemistry II | CHEM 1120 and more Assignments Chemistry in PDF only on Docsity!

Balance the following reactions using the Half-Reaction technique. Refer to the instructions and the example of the permanganate-oxalate reaction.

  1. Fe3+^ + I-^ โ†’ Fe2+^ + I (^2) 1 x 2I-^ โ†’ I2 + 2e- 2 x Fe3+^ + 1e -^ โ†’ Fe 2+

2Fe3+^ + 2I -^ โ†’ 2Fe2+^ + I

  1. Cl2 + Br -^ โ†’ Br2 + Cl - 1 x 2Br-^ โ†’ Br 2 + 2e- 1 x Cl2 + 2e -^ โ†’ 2Cl-

Cl2 + 2Br -^ โ†’ Br 2 + 2Cl -

  1. Zn + Hg 2 2+^ โ†’ Zn2+^ + Hg 1 x Zn โ†’ Zn 2+^ + 2e- 1 x 2e-^ + Hg 2 2+^ โ†’ 2Hg

Zn + Hg 2 2+^ โ†’ Zn 2+^ + 2Hg

  1. I-^ + ClO 4 -^ + H +^ โ†’ I2 + ClO 3 -^ + H 2 O 1 x 2e-^ + ClO 4 -^ + 2H +^ โ†’ ClO 3 -^ + H 2 O 1 x 2I-^ โ†’ I2 + 2e-

2I-^ + ClO 4 -^ + 2H +^ โ†’ I2 + ClO 3 -^ + H 2 O

  1. Cu + NO 3 -^ + H +^ โ†’ Cu2+^ + NO 2 -^ + H2 O 1 x Cu โ†’ Cu2+^ + 2e - 1 x 2e-^ + NO 3 -^ + 2H +^ โ†’ NO2-^ + H 2 O

Cu + NO 3 -^ + 2H +^ โ†’ Cu2+^ + NO 2 -^ + H 2 O

  1. H2S + Cr 2 O72-^ + H +^ โ†’ Cr 3+^ + S 8 + H 2 O 8 x 6e-^ + Cr 2 O72-^ + 14H +^ โ†’ 2Cr3+^ + 7H 2 O 3 x 8H 2 S โ†’ S 8 + 16H +^ + 16e -

24H2S + 8Cr 2 O72-^ + 64H+^ โ†’ 16Cr3+^ + 3S 8 + 56H 2 O

  1. MnO 4 -^ + C 2 O4 2 -^ + OH -^ โ†’ MnO 2 + CO 3 2-^ + H 2 O 2 x MnO4-^ + 3e -^ + 2H 2 O โ†’ MnO 2 + 4OH - 3 x C2O42-^ + 4OH -^ โ†’ 2CO32-^ + 2H2 O + 2e-

2MnO4-^ + 3C 2 O42-^ + 4OH -^ โ†’ 2MnO 2 + 6CO 3 2-^ + 2H 2 O

Balance the following in acid solution. (To balance the oxygen, add H+s to one side of the reaction and H 2 Os to the other side.)

  1. MnO 4 โˆ’^ + NO 2 โˆ’^ โ†’ Mn2+^ + NO 3 โˆ’ 2ร— MnO 4 โˆ’^ + 5e โˆ’^ + 8H +^ โ†’ Mn 2+^ + 4H 2 O 5ร— H 2 O + NO 2 โˆ’^ โ†’ 2H+^ + NO 3 โˆ’^ + 2e โˆ’ 6H+^ + 2MnO 4 โˆ’^ + 5NO2โˆ’^ โ†’ 2Mn 2+^ + 5NO 3 โˆ’^ + 3H 2 O

  2. Cu + NO 3 โˆ’^ โ†’ NO + Cu 2+ 2ร— 4H+^ + 3e โˆ’^ + NO3โˆ’^ โ†’ NO + 2H 2 O 3ร— Cu โ†’ Cu 2+^ + 2e โˆ’ 3Cu + 2NO 3 โˆ’^ + 8H+^ โ†’ 2NO + 3Cu 2+^ + 4H 2 O

  3. Fe3+^ + Cr 3+^ โ†’ Cr2O 7 2โˆ’^ + Fe 2+ 6ร— 1eโˆ’^ + Fe 3+^ โ†’ Fe2+ 1ร— 7H2O + 2Cr 3+^ โ†’ Cr 2 O72โˆ’^ + 6e โˆ’^ + 14H + 6Fe3+^ + 7H 2 O + 2Cr3+^ โ†’ Cr 2 O72โˆ’^ + 6Fe 2++ 14H +

  4. MnO4โˆ’^ + H 2 O โ†’ Mn2+^ + H2 O 5ร— 2H 2 O โ†’ H 2 O2 + 2e โˆ’^ + 2H + 2ร— MnO 4 โˆ’^ + 5e โˆ’^ + 8H +^ โ†’ Mn 2+^ + 4H 2 O 2MnO4โˆ’^ + 2H 2 O + 6H+^ โ†’ 2Mn2+^ + 5H 2 O

  5. AuCl4โˆ’^ + Hg โ†’ Au + Hg 2 Cl2 + Cl โˆ’ 2ร— AuCl 4 โˆ’^ + 3e โˆ’^ โ†’ Au + 4Cl โˆ’ 3ร— 2Cl โˆ’^ + 2Hg โ†’ Hg2Cl 2 + 2e โˆ’ 2AuCl4โˆ’^ + 6Hg โ†’ 2Au + 3Hg 2 Cl 2 + 2Cl โˆ’

13) NO 3 โˆ’^ + SO 2 โ†’ SO42โˆ’^ + NO

2ร— NO3โˆ’^ + 3e โˆ’^ + 4H+^ โ†’ 2H2O + NO 3ร— 2H2O + SO 2 โ†’ SO42โˆ’^ + 2e โˆ’^ + 4H + 2H2O + 2NO 3 โˆ’^ + 3SO 2 โ†’ 3SO 4 2โˆ’^ + 2NO + 4H +

  1. N 2 H5+^ + SbCl 4 โˆ’^ โ†’ SbCl6โˆ’^ + NH 4 + (Hint: Clโˆ’^ is also present.) 1ร— 2Cl โˆ’^ + SbCl 4 โˆ’^ โ†’ SbCl6โˆ’^ + 2e โˆ’ 1ร— N2H5+^ + 3H +^ + 2eโˆ’^ โ†’ 2NH4+ 3H+^ + 2Cl โˆ’^ + N 2 H5+^ + SbCl 4 โˆ’^ โ†’ SbCl 6 โˆ’^ + 2NH 4 +