1. What is Ka?

Ka (acid dissociation constant) is a quantitative measure of the strength of an acid in solution. It represents the equilibrium constant for the dissociation reaction of an acid and indicates how completely an acid dissociates in water.

2. How Does the Calculator Work?

The calculator uses the Ka formula:

Where:

• \( [H^+] \) — Hydrogen ion concentration (M)
• \( C \) — Initial concentration of the acid (M)
• \( Ka \) — Acid dissociation constant (M)

Explanation: The formula calculates Ka from pH measurements and initial acid concentration, assuming the acid is weak and follows typical dissociation behavior.

3. Importance of Ka Calculation

Details: Ka values are crucial for understanding acid strength, predicting chemical behavior in solutions, calculating pH of acid solutions, and designing buffer systems in chemistry and biochemistry.

4. Using the Calculator

Tips: Enter pH value (0-14) and initial acid concentration in molarity (M). Ensure concentration is greater than [H⁺] concentration for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between Ka and pKa?
A: pKa = -log(Ka). Smaller pKa values indicate stronger acids, while larger pKa values indicate weaker acids.

Q2: When is this calculation valid?
A: This calculation is most accurate for weak acids where [H⁺] is significantly less 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 can have Ka values as small as 10⁻¹⁰ or less.

Q4: Can this be used for polyprotic acids?
A: This formula is primarily for monoprotic acids. Polyprotic acids require more complex calculations for each dissociation step.

Q5: What are common sources of error?
A: Temperature variations, ionic strength effects, and measurement inaccuracies in pH and concentration can affect the calculated Ka value.