pKa: -log(Ka), where Ka is acid dissociation constant
[Salt]: Molar concentration of the conjugate base (salt)
[Acid]: Molar concentration of the weak acid
Common Mistakes
Students often confuse strong acids/bases with weak ones, applying incorrect formulas (e.g., assuming complete dissociation for weak electrolytes).
Don't ignore the common ion effect in solubility problems or buffer calculations; it significantly impacts concentrations.
Miscalculating the hydrolysis constant (Kh) or the degree of hydrolysis (h) for salt solutions, leading to incorrect pH values.
Rapid Revision
Ionic equilibrium covers acid-base definitions, pH, buffer action, hydrolysis of salts, and solubility product. Remember Henderson-Hasselbalch for buffers, Ksp principles for solubility, and the common ion effect's impact. Always distinguish between strong and weak electrolytes.
Frequently Asked Questions
What is a buffer solution and why is it important in chemistry?▾
A buffer solution is a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It resists significant changes in pH upon the addition of small amounts of acid or base. This property is crucial in biological systems and many chemical processes where maintaining a stable pH is essential.
How does the common ion effect influence the solubility of sparingly soluble salts?▾
The common ion effect reduces the solubility of a sparingly soluble salt when a soluble salt containing a common ion is added to the solution. According to Le Chatelier's principle, the equilibrium shifts to form more solid precipitate, thus decreasing the concentration of the dissolved ions and lowering the solubility of the sparingly soluble salt.
What is the difference between Ka and pKa, and how are they related to acid strength?▾
Ka is the acid dissociation constant, which quantifies the strength of an acid in solution; a larger Ka indicates a stronger acid. pKa is the negative logarithm of Ka (pKa = -log Ka). A smaller pKa value corresponds to a larger Ka, meaning a stronger acid, while a larger pKa indicates a weaker acid.
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