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Definition: This calculator determines the acid dissociation constant (pKa) for salts formed from weak acids and weak bases using pH and pKb values.
Purpose: It helps chemists understand the acid-base properties of salts in solution, important for buffer preparation and chemical analysis.
The calculator uses the formula:
Where:
Explanation: The formula relates the acid strength of the salt to the solution pH and the base strength of the parent compound.
Details: Knowing pKa helps predict salt behavior in solution, including hydrolysis, buffer capacity, and solubility characteristics.
Tips: Enter the solution pH and the pKb value of the weak base. Both values are required for calculation.
Q1: What is the typical range for pKa values?
A: pKa values typically range from -10 (very strong acids) to 50 (very weak acids), with most between 0-14.
Q2: How does temperature affect the calculation?
A: Temperature affects pH and pKb values. The formula assumes standard conditions (25°C).
Q3: Can this be used for strong acid/strong base salts?
A: No, this formula applies only to salts of weak acids and weak bases which hydrolyze in solution.
Q4: What if I only know Ka and Kb?
A: Convert them first: pKa = -log(Ka), pKb = -log(Kb) before using this calculator.
Q5: How accurate is this calculation?
A: It provides theoretical values. Actual values may vary due to ionic strength and activity coefficients.