Chemistry / Unit 10 Chem 1835 short lesson, about 20 seconds
Weak Acid Equilibrium and Ka
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The idea
A weak acid ionizes only partially in water, and Ka, its acid ionization constant, measures how far that equilibrium favors ions over the intact acid.
In practice
Acetic acid's Ka expression is [H3O+][CH3COO−]/[CH3COOH], a genuine equilibrium rather than a completed reaction.
Where people slip
Water does not belong in the Ka expression's denominator, and a weak acid's ionization is not complete, so molarity cannot substitute for [H3O+].
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- 1841The Ka–Kb Relationship for a Conjugate Pair
- 1844Solving for pH of a Weak Acid Solution
- 1847Percent Ionization Defined
- 1853Polyprotic Acids: Stepwise Ionization
- 1865Acid-Base Indicators: Mechanism
- 1887Buffers: How They Resist pH Change
- 1893Henderson-Hasselbalch Equation Application
- 1899Capstone: Buffer pH Calculation
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