Redox Reactions Lecture Notes

Introduction to Redox Reactions

• Redox reactions involve both oxidation and reduction occurring simultaneously.
• Oxidation: gaining of oxygen or loss of electrons.
• Reduction: loss of oxygen or gain of electrons.
• Mnemonic: OIL RIG (Oxidation Is Loss, Reduction Is Gain) referring to electrons.

Oxidation and Reduction

• Example: Magnesium atom
  • Oxidation: Magnesium loses 2 electrons to become Mg²⁺ (oxidized).
  • Reduction: Gains electrons back becoming neutral magnesium (reduced).
• Redox reactions always involve simultaneous oxidation and reduction due to electron transfer.

Example: Magnesium and Dilute Acid

• Magnesium reacts with dilute acid (H⁺) leading to:
  • Magnesium loses electrons (oxidized to Mg²⁺).
  • Hydrogen ions gain electrons (reduced to hydrogen gas).

Displacement Reactions

• More reactive metals displace less reactive metals.
• Reactivity series example:
  • Calcium (more reactive) displaces iron in iron sulfate, forming calcium sulfate and solid iron.

Ionic Equations

• Focus on particles changing or taking part in reactions.
• Spectator ions: particles that do not change in the reaction (e.g., sulfate ions in examples).
• Ionic equation removes spectator ions.

Half Equations

• Used to show gain and loss of electrons for each element.
• Example: Calcium and iron in the displacement reaction.
  • Calcium: Ca → Ca²⁺ + 2e⁻.
  • Iron: Fe²⁺ + 2e⁻ → Fe.
• Ensure overall charge balance in half equations:
  • Check charges on both sides for balance (e.g., iron half equation charges balance to zero).

Conclusion

• Redox reactions crucial for understanding chemical processes.
• Use tools like ionic and half equations for clarity.
• Share and discuss with peers for enhanced learning.

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