1. What is Ka Calculation from pH and Molarity?

The Ka calculation from pH and molarity determines the acid dissociation constant (Ka) of a weak acid solution using its pH value and molar concentration. This provides important information about the acid's strength and dissociation behavior.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Ka \) — Acid dissociation constant (mol/L)
• \( pH \) — pH value of the solution (dimensionless)
• \( C \) — Molar concentration of the acid (mol/L)
• \( 10^{-pH} \) — Hydrogen ion concentration [H⁺] (mol/L)

Explanation: This formula calculates the equilibrium constant for weak acid dissociation based on the measured pH and known initial concentration.

3. Importance of Ka Calculation

Details: Calculating Ka is essential for understanding acid strength, predicting buffer capacity, and studying acid-base equilibrium in chemical and biological systems.

4. Using the Calculator

Tips: Enter pH value (0-14) and molar concentration (mol/L). The pH should be measured accurately, and concentration must be greater than the hydrogen ion concentration for valid results.

5. Frequently Asked Questions (FAQ)

Q1: What does Ka represent?
A: Ka represents the acid dissociation constant, which indicates the strength of an acid. Larger Ka values indicate stronger acids.

Q2: When is this calculation valid?
A: This calculation is valid for weak acids where the approximation [H⁺] ≈ √(Ka×C) holds true and C > [H⁺].

Q3: What are typical Ka values?
A: Ka values range from about 10⁻¹⁰ for very weak acids to 10¹⁰ for very strong acids. Most weak acids have Ka values between 10⁻² and 10⁻⁵.

Q4: Can this be used for strong acids?
A: No, this calculation is specifically for weak acids. Strong acids are assumed to dissociate completely.

Q5: What if C ≤ [H⁺]?
A: The calculation becomes invalid if concentration C is less than or equal to the hydrogen ion concentration, as this violates the underlying assumptions of the formula.