1. What is Percent Dissociation in Water?

Percent dissociation in water represents the fraction of water molecules that dissociate into hydrogen (H⁺) and hydroxide (OH⁻) ions at equilibrium. It quantifies the extent of water's autoionization process.

2. How Does the Calculator Work?

The calculator uses the percent dissociation formula:

Where:

• \( K_w \) — Ion product of water (typically 1.0 × 10⁻¹⁴ M² at 25°C)
• \( [H_2O] \) — Concentration of water (typically 55.5 M)

Explanation: The formula calculates the percentage of water molecules that undergo dissociation based on the equilibrium constant and water concentration.

3. Importance of Percent Dissociation Calculation

Details: Understanding water's dissociation is fundamental in acid-base chemistry, pH calculations, and predicting the behavior of aqueous solutions. It helps explain water's amphoteric nature and its role as both an acid and a base.

4. Using the Calculator

Tips: Enter Kw value in M² (typically 1.0e-14) and water concentration in M (typically 55.5). Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical percent dissociation of pure water?
A: At 25°C with Kw = 1.0 × 10⁻¹⁴ and [H₂O] = 55.5 M, the percent dissociation is approximately 1.8 × 10⁻⁷%, showing that water is a very weak electrolyte.

Q2: How does temperature affect percent dissociation?
A: Kw increases with temperature, so percent dissociation also increases. At higher temperatures, more water molecules dissociate.

Q3: Why is water concentration considered constant?
A: In dilute aqueous solutions, water concentration remains nearly constant at 55.5 M because the dissociation is extremely small relative to the total water molecules.

Q4: Can this formula be used for other solvents?
A: The concept applies to other amphoteric solvents, but the specific formula and constants would differ based on the solvent's properties.

Q5: How is percent dissociation related to pH?
A: Percent dissociation helps explain why pure water has pH = 7 at 25°C. The small dissociation produces equal concentrations of H⁺ and OH⁻ ions (10⁻⁷ M each).