Oxidation and Reduction (Redox) | Jamb Chemistry

Oxidation in Terms of Addition of Oxygen or Removal of Hydrogen

1. Oxidation involves the addition of oxygen to a substance.
2. Combustion is a common example of oxidation (e.g., $C + O_2 \rightarrow CO_2$).
3. Metal oxides form by oxidation of metals (e.g., $2Mg + O_2 \rightarrow 2MgO$).
4. Oxidation can also mean the removal of hydrogen from a compound.
5. Ethanol oxidizes to acetaldehyde by losing hydrogen ($C_2H_5OH \rightarrow CH_3CHO + H_2$).
6. Oxidation reactions often release energy, such as in respiration.
7. Oxidation is common in organic chemistry, especially in alcohol to ketone or aldehyde conversions.
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Reduction as Removal of Oxygen or Addition of Hydrogen

8. Reduction is the removal of oxygen from a compound.
9. Copper(II) oxide reduces to copper by removing oxygen ($CuO + H_2 \rightarrow Cu + H_2O$).
10. Addition of hydrogen is another form of reduction (e.g., $C_2H_4 + H_2 \rightarrow C_2H_6$).
11. Reduction is key in industrial processes like the extraction of metals.
12. In biological systems, reduction occurs during photosynthesis.
13. Reduction reactions are vital in the energy storage of cells (e.g., ATP formation).
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Oxidation and Reduction in Terms of Electron Transfer

14. Oxidation is the loss of electrons by an atom or molecule ($Na \rightarrow Na^+ + e^-$).
15. Reduction is the gain of electrons ($Cl_2 + 2e^- \rightarrow 2Cl^-$).
16. Oxidation and reduction always occur together in a redox reaction.
17. The reducing agent donates electrons and becomes oxidized.
18. The oxidizing agent accepts electrons and becomes reduced.
19. Redox reactions power batteries and electrochemical cells.
20. In galvanic cells, oxidation occurs at the anode.
21. Reduction takes place at the cathode in galvanic cells.
22. Electron transfer drives processes like corrosion and metal plating.
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Use of Oxidation Numbers

23. Oxidation numbers indicate the charge an atom would have if bonds were ionic.
24. Free elements have an oxidation number of 0 (e.g., $O_2, N_2$).
25. Hydrogen is typically $+1$ except in hydrides ($-1$).
26. Oxygen usually has $-2$ except in peroxides ($-1$).
27. The sum of oxidation numbers in a neutral compound is 0.
28. In polyatomic ions, the sum equals the ion’s charge.
29. Alkali metals always have $+1$ oxidation numbers in compounds.
30. Assigning oxidation numbers helps track redox reactions.
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Oxidation and Reduction as Change in Oxidation Number

31. Oxidation corresponds to an increase in oxidation number.
32. Reduction corresponds to a decrease in oxidation number.
33. In $Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$, $Zn$ is oxidized, and $Cu$ is reduced.
34. The oxidation number of the oxidizing agent decreases.
35. The oxidation number of the reducing agent increases.
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Balancing Equations Using Oxidation Numbers

36. Redox equations can be balanced using oxidation numbers.
37. Identify the elements undergoing oxidation and reduction.
38. Write oxidation and reduction half-reactions.
39. Balance atoms and charges in each half-reaction.
40. Combine half-reactions to form the overall balanced equation.
41. Ensure the total increase in oxidation numbers equals the total decrease.
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IUPAC Nomenclature Using Oxidation Numbers

42. Oxidation numbers are shown in Roman numerals in parentheses.
43. $FeCl_3$ is named iron(III) chloride.
44. $Cu_2O$ is copper(I) oxide.
45. $MnO_4^-$ is permanganate, where manganese is in the $+7$ state.
46. $PbO_2$ is lead(IV) oxide.
47. Naming based on oxidation states avoids ambiguity for compounds like $FeCl_2$ and $FeCl_3$.
48. Oxidation states are essential in naming coordination compounds (e.g., $[Cr(NH_3)_6]^{3+}$, chromium(III)).
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Tests for Oxidizing Agents

49. Oxidizing agents gain electrons in a reaction.
50. Common oxidizing agents include $KMnO_4, K_2Cr_2O_7, H_2O_2$.
51. $KMnO_4$ turns colorless or brown when reduced.
52. $K_2Cr_2O_7$ changes from orange to green upon reduction.
53. Oxidizing agents are used in bleaching and disinfection.
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Tests for Reducing Agents

54. Reducing agents lose electrons during reactions.
55. Examples of reducing agents include $Na_2SO_3, FeSO_4, H_2$.
56. $Na_2SO_3$ reduces $KMnO_4$, decolorizing it.
57. Reducing agents turn iodine solution from brown to colorless.
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Examples of Oxidizing and Reducing Agents in Reactions

58. $Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$: $Zn$ is reducing agent, $Cu^{2+}$ is oxidizing agent.
59. Hydrogen reduces metal oxides to pure metals (e.g., $Fe_2O_3 + 3H_2 \rightarrow 2Fe + 3H_2O$).
60. $Cl_2$ acts as an oxidizing agent in water purification.
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Applications of Redox Reactions

61. Redox reactions are fundamental in energy production in batteries.
62. Industrial extraction of metals involves reduction processes.
63. Oxidation is used in chemical synthesis (e.g., producing acids).
64. Reduction reactions are used in fuel cells and hydrogen energy systems.
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    ####### Hydrolysis of Salts and Their Redox Nature
65. Salt hydrolysis determines solution pH.
66. Acidic salts (e.g., $NH_4Cl$) lower pH by releasing $H^+$.
67. Basic salts (e.g., $CH_3COONa$) increase pH by releasing $OH^-$.
68. Redox reactions in salts influence water treatment.
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Balancing and Predicting Redox Reactions

69. Half-reaction methods simplify balancing complex redox reactions.
70. Predicting reactivity uses the electrochemical series.
71. Metals like $Zn$ reduce $Cu^{2+}$ due to higher reducing power.
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Industrial and Environmental Significance

72. Corrosion of metals involves redox.
73. Electroplating uses redox for surface coatings.
74. Disinfection with oxidizing agents (e.g., chlorine) ensures water safety.
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Biological Redox Systems

75. Cellular respiration involves oxidation of glucose.
76. Photosynthesis reduces $CO_2$ into glucose.
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Miscellaneous

77. Redox reactions power combustion engines.
78. Understanding redox is crucial in environmental cleanup.
79. Oxidation numbers simplify reaction mechanisms.
80. $O_2$ is a common oxidizing agent in everyday reactions.
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Further Tests

81. Flame tests detect metals in redox states.
82. $H_2O_2$ bubbles when reacting with reducing agents.
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Balancing Advanced Reactions

83. Balancing is crucial in reactions like $KMnO_4 + H_2O_2$.
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Electrochemistry

84. Redox drives electrochemical reactions in batteries.
85. $Li$-ion cells involve redox for charging/discharging.
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Environmental Impacts

86. Redox reactions in soil affect nutrient cycling.
87. Oxidation in the atmosphere forms pollutants.
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Advanced Nomenclature

88. Naming polyatomic ions includes oxidation states.
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Oxidation of Organic Compounds

89. Alcohols oxidize to aldehydes or ketones.
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Conclusion

90. Mastery of redox is critical in chemistry and real-life applications.

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