1. What is pKa?

pKa is the negative base-10 logarithm of the acid dissociation constant (Ka) of a solution. It provides a quantitative measure of the strength of an acid in solution.

2. How Does the Calculator Work?

The calculator uses the pKa equation:

Where:

• \( pKa \) — Acid dissociation constant on logarithmic scale (dimensionless)
• \( Ka \) — Acid dissociation constant (dimensionless)

Explanation: The pKa value indicates the strength of an acid. The smaller the pKa, the stronger the acid.

3. Importance of pKa Calculation

Details: pKa is crucial in chemistry and biochemistry for understanding protonation states, drug absorption, protein binding, and chemical reaction mechanisms.

4. Using the Calculator

Tips: Enter the Ka value (must be positive). The calculator will compute the corresponding pKa value.

5. Frequently Asked Questions (FAQ)

Q1: What's the relationship between pKa and pH?
A: pH measures the acidity of a solution, while pKa measures the inherent strength of an acid. The Henderson-Hasselbalch equation relates them.

Q2: What are typical pKa values?
A: Strong acids have pKa < 0, weak acids 0-14, and very weak acids >14. Most biological acids have pKa between 2-12.

Q3: How does temperature affect pKa?
A: pKa values are temperature-dependent, as Ka changes with temperature according to van't Hoff equation.

Q4: What's the difference between pKa and pKb?
A: pKa measures acid strength, while pKb measures base strength. For conjugate pairs: pKa + pKb = pKw (14 at 25°C).

Q5: Can pKa be negative?
A: Yes, for very strong acids where Ka > 1, pKa will be negative (e.g., HCl has pKa ≈ -7).