1. What is the Dissociation Constant of a Weak Base?

Definition: The dissociation constant (K_b) measures the extent to which a weak base dissociates in water to form hydroxyl ions and its conjugate acid.

Purpose: It quantifies the base strength and helps predict the equilibrium concentrations of species in solution.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( K_b \) — Dissociation constant of weak base
• \( [OH^-] \) — Concentration of hydroxyl ions (mol/m³)
• \( [B^+] \) — Concentration of cations (mol/m³)
• \( [BOH] \) — Concentration of undissociated weak base (mol/m³)

Explanation: The product of hydroxyl ion and cation concentrations divided by the concentration of undissociated base gives the equilibrium constant.

3. Importance of Dissociation Constant

Details: K_b values help predict base strength, calculate pH of solutions, and understand chemical equilibrium in acid-base reactions.

4. Using the Calculator

Tips: Enter concentrations of hydroxyl ions, cations, and undissociated base in mol/m³. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical K_b values for weak bases?
A: Weak bases typically have K_b values between 10⁻² and 10⁻¹², with smaller values indicating weaker bases.

Q2: How does temperature affect K_b?
A: Like all equilibrium constants, K_b is temperature-dependent, generally increasing with temperature for endothermic dissociations.

Q3: What's the relationship between K_b and pK_b?
A: pK_b = -log(K_b). Lower pK_b values indicate stronger bases.

Q4: How can I find these concentrations experimentally?
A: Measure pH to find [OH⁻], then use stoichiometry and mass balance to determine [B⁺] and [BOH].

Q5: What units should I use for concentrations?
A: The calculator uses mol/m³, but you can convert from mol/L (M) by multiplying by 1000 (1 M = 1000 mol/m³).