Balancing REDOX Reactions Quiz

Reduction-Oxidation reactions (REDOX reactions) involve the gain and loss of electrons.

What method do we use to balance REDOX reactions?

What happens during oxidation?

What happens during reduction?

In the same reaction K (s) + Br2 (l) → KBr (aq), what species is reduced?

The oxidation half-reaction for K is K0 → K+ + ______

In the reaction K (s) + Br2 (l) → KBr (aq), what species is oxidized?

The reduction half-reaction for Br2 is Br20 + ______ → 2Br¯

What is the balanced overall reaction for 2K (s) + Br2 (l)?

Are Au3+ + I¯ → Au + I2 a REDOX reaction?

Are Cu + Ag+ → Cu2+ + Ag a REDOX reaction?

Is BaSO3 → BaO + SO2 a REDOX reaction?

In an acidic solution, which species in the reaction ClO3¯ + I2 → IO3¯ + Cl¯ is being oxidized?

In the same reaction ClO3¯ + I2 → IO3¯ + Cl¯, which species is being reduced?

REDOX Reactions Overview

REDOX reactions involve the transfer of electrons between species, where one species is oxidized (loses electrons) and another is reduced (gains electrons).
Charge conservation is maintained through simultaneous oxidation and reduction.
Assigning oxidation numbers is crucial for identifying oxidized and reduced species.

Key Definitions

Oxidation: Loss of electrons, increasing positive charge.
Reduction: Gain of electrons, increasing negative charge.

Balancing REDOX Reactions

Use the half-reactions method for balancing.
Identify oxidation and reduction half-reactions separately.

Example Problem: Balancing K + Br2 → KBr

Assign oxidation numbers:
- K: 0 (elemental state) to +1 (in KBr).
- Br2: 0 to -1 (in KBr).
Oxidation half-reaction: K → K⁺ + e⁻
Reduction half-reaction: Br2 + 2e⁻ → 2Br⁻
Balance charges by adding electrons to the appropriate sides:
- Oxidation: K → K⁺ + e⁻
- Reduction: Br2 + 2e⁻ → 2Br⁻
Multiply the oxidation half-reaction by 2 to equalize electrons:
- 2K → 2K⁺ + 2e⁻
Combine half-reactions, cancelling out electrons:
- 2K + Br2 → 2K⁺ + 2Br⁻
Balanced equation: 2K (s) + Br2 (l) → 2KBr (aq)

Practice REDOX Reactions

Confirm if a reaction is a REDOX reaction and balance it using the half-reaction method:
- Au³⁺ + I⁻ → Au + I2
- Cu + Ag⁺ → Cu²⁺ + Ag
- BaSO3 → BaO + SO2

Complex REDOX Reactions

In aqueous solutions, especially in acidic or basic conditions, protons (H⁺) and hydroxides (OH⁻) play a significant role in balancing charges and species in half-reactions.
Example in acidic solution:
- ClO3⁻ + I2 → IO3⁻ + Cl⁻
Assign oxidation numbers to ascertain which species are oxidized and reduced before balancing.

Test your knowledge on balancing REDOX reactions in chemistry. This quiz covers the principles of oxidation and reduction, including how to assign oxidation numbers to reactants and products. Gain a deeper understanding of these essential chemical processes through practice questions.