1. What is Ka Calculation From pH?

The acid dissociation constant (Ka) calculation from pH allows determination of the strength of a weak acid. It quantifies the extent to which an acid donates protons in aqueous solution.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Ka \) — Acid dissociation constant (mol/L)
• \( [H^+] \) — Hydrogen ion concentration (mol/L)
• \( C \) — Initial concentration of acid (mol/L)
• \( pH \) — Negative logarithm of hydrogen ion concentration

Explanation: This formula applies to weak acids where the concentration of H⁺ ions is small compared to the initial acid concentration.

3. Importance of Ka Calculation

Details: Ka values are fundamental in acid-base chemistry, helping determine acid strength, predict reaction outcomes, and understand buffer systems in biological and chemical processes.

4. Using the Calculator

Tips: Enter pH value (0-14) and acid concentration in mol/L. The concentration must be greater than the calculated [H⁺] concentration for valid results.

5. Frequently Asked Questions (FAQ)

Q1: What does a larger Ka value indicate?
A: A larger Ka value indicates a stronger acid that dissociates more completely in aqueous solution.

Q2: When is this calculation valid?
A: This calculation is valid for weak acids where [H⁺] is much smaller than the initial concentration C.

Q3: What are typical Ka values?
A: Strong acids have Ka > 1, weak acids have Ka < 1. Very weak acids have Ka values in the range of 10⁻⁵ to 10⁻¹⁰.

Q4: How does temperature affect Ka?
A: Ka values are temperature-dependent. The dissociation constant typically increases with temperature for endothermic dissociation reactions.

Q5: Can this be used for polyprotic acids?
A: This simplified formula is primarily for monoprotic weak acids. Polyprotic acids require more complex calculations considering multiple dissociation steps.