Chapter 16
Acid-Base Equilibria
By Boundless
The equilibrium constants for homogeneous and heterogeneous solutions need to be calculated differently.
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The common ion effect describes the changes that occur with the introduction of ions to a solution containing that same ion.
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A buffer is a solution of weak acid and conjugate base or weak base and conjugate acid used to resist pH change with added solute.
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The pH of a buffer solution can be calculated from the equilibrium constant and the initial concentration of the acid.
The Henderson–Hasselbalch equation connects the measurable value of the pH of a solution with the theoretical value pKa.
The changed pH of a buffer solution in response to the addition of an acid or a base can be calculated.
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An alkaline buffer can be made from a mixture of the base and its conjugate acid, but the formulas for determining pH take a different form.
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The pH of a buffer depends on the ratio [base]/[acid] rather than on the particular concentration of a specific solution.
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For an effective buffer, there must be enough acid/conjugate base to consume all newly added ions so that the pH is maintained.
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A buffer's capacity is the pH range where it works as an effective buffer, preventing large changes in pH upon addition of an acid or base.
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A strong acid will react with a strong base to form a neutral (pH = 7) solution.
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A weak acid will react with a strong base to form a basic (pH > 7) solution.
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A strong acid will react with a weak base to form an acidic (pH < 7) solution.
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Polyprotic acids, also known as polybasic acids, are able to donate more than one proton per acid molecule.
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An indicator is a weak acid (or a weak base) that has different colors in its dissociated and undissociated states.
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The solubility product is the equilibrium constant representing the maximum amount of solid that can be dissolved in aqueous solution.
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Molar solubility is the number of moles of a solute that can be dissolved per liter of solution before the solution becomes saturated.
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A set of rules can be used to predict whether a combination of cations and anions in solution will recombine and precipitate.
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By changing the pH of the solution, you can change the charge state of the solute.
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Fractional precipitation can be used to determine which ions are present in a solution by taking advantage of their different solubilities.
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Adding a common ion decreases the solubility of a solute, causing it to precipitate.