(SHORT) Explaining Redox Reactions in Acids and Metals

Key Terms/Concepts

• Redox Reaction: A chemical reaction involving the transfer of electrons between two species, resulting in oxidation and reduction processes.

• Oxidation Number (ON): A value assigned to an element in a compound that represents the number of electrons lost or gained by that element.

• Oxidant: A substance that gains electrons in a redox reaction, causing another substance to be oxidized.

• Reductant: A substance that loses electrons in a redox reaction, causing another substance to be reduced.

Key Reactions

Key Observations

• Colourless Solution: Indicates the presence of dissolved ions in the solution.

• Bubbles of Colourless Gas (H₂): Observed during the reaction, indicating the formation of hydrogen gas.

Key Equations

• Overall Reaction: 2 Na + 2 H+ -> 2 Na+ + H₂

• Balanced Half Equations:

  • For Hydrogen: 2 H+ + 2 e- -> H₂

  • For Sodium: 2 Na -> 2 Na+ + 2 e-

Key Principles

• Conservation of Charge: The number of electrons lost in oxidation must equal the number of electrons gained in reduction.

• Balancing Redox Reactions: Ensure that the number of electrons is the same on both sides of the equation.

Facts to Memorize

• Oxidation number of H₂ is 0.

• Oxidation number of Na is 0 in elemental form.

• Balanced half equation for hydrogen: 2 H⁺ + 2 e⁻ -> H₂.

• Balanced half equation for sodium: Na -> Na⁺ + e⁻.

Concept Comparisons

Cause and Effect