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Weak Acid-Strong Base Equivalence Point Formula:
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The pH calculation at the equivalence point for weak acid-strong base titrations determines the pH when exactly enough strong base has been added to neutralize the weak acid. At this point, the solution contains the conjugate base of the weak acid, resulting in a basic pH.
The calculator uses the equivalence point formula:
Where:
Explanation: This formula accounts for the hydrolysis of the conjugate base formed at the equivalence point, where the pH is determined by the basic salt solution.
Details: Accurate pH calculation at equivalence point is crucial for understanding titration curves, determining appropriate indicators, and predicting the behavior of weak acid-strong base systems in analytical chemistry and laboratory applications.
Tips: Enter the pKa value of the weak acid and the concentration of the resulting salt solution in mol/L. Both values must be positive numbers greater than zero for accurate calculation.
Q1: Why is the pH basic at equivalence point for weak acid-strong base?
A: The conjugate base of the weak acid hydrolyzes with water, producing hydroxide ions and resulting in a basic solution.
Q2: What is the typical pH range at equivalence point?
A: Typically ranges from 7 to 14, depending on the strength of the weak acid (pKa value) and concentration.
Q3: How does pKa affect the equivalence point pH?
A: Higher pKa values (weaker acids) result in higher pH values at equivalence point due to stronger conjugate bases.
Q4: What indicators are suitable for weak acid-strong base titrations?
A: Phenolphthalein (pH 8.3-10.0) is commonly used as it changes color in the basic range where equivalence occurs.
Q5: Can this formula be used for strong acid-weak base titrations?
A: No, this specific formula applies only to weak acid-strong base systems. Strong acid-weak base systems have different equivalence point calculations.