1. What is pKa given Dissociation Constant of Weak Acid?

Definition: pKa is the negative base-10 logarithm of the acid dissociation constant (Ka) of a solution.

Purpose: It provides a convenient way to express the strength of weak acids, with lower pKa values indicating stronger acids.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( pK_a \) — Negative log of acid ionization constant
• \( K_a \) — Acid dissociation constant

Explanation: The logarithm converts the very small Ka values (typically 10^-3 to 10^-10) into more manageable positive numbers.

3. Importance of pKa Calculation

Details: pKa values are crucial in chemistry for predicting acid-base behavior, buffer preparation, and understanding reaction mechanisms.

4. Using the Calculator

Tips: Enter the acid dissociation constant (Ka) value. The default value is 0.00001 (10^-5). The value must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does a higher pKa value indicate?
A: A higher pKa indicates a weaker acid, as it corresponds to a smaller Ka value (less dissociation).

Q2: What's the relationship between pKa and pH?
A: pKa is a property of the acid itself, while pH depends on the solution's concentration. When pH = pKa, the acid is 50% dissociated.

Q3: What's a typical pKa range for weak acids?
A: Most weak acids have pKa values between 2 and 12 in aqueous solutions at 25°C.

Q4: Can pKa be negative?
A: Yes, for very strong acids with Ka > 1, the pKa will be negative.

Q5: How precise should my pKa value be?
A: For most applications, 2 decimal places are sufficient, though research applications may require more precision.