Properties of Buffers - AP Chemistry
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What is the buffer capacity?
What is the buffer capacity?
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The amount of acid or base a buffer can neutralize before pH changes significantly. Measures how much acid/base can be added before breakdown.
The amount of acid or base a buffer can neutralize before pH changes significantly. Measures how much acid/base can be added before breakdown.
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What is the pH of a buffer if $pK_a = 6.5$ and $[\text{A}^-]/[\text{HA}] = 10$?
What is the pH of a buffer if $pK_a = 6.5$ and $[\text{A}^-]/[\text{HA}] = 10$?
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pH = 7.5. Using Henderson-Hasselbalch: pH = 6.5 + log(10) = 7.5.
pH = 7.5. Using Henderson-Hasselbalch: pH = 6.5 + log(10) = 7.5.
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What is the maximum buffer capacity condition?
What is the maximum buffer capacity condition?
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When $[\text{HA}] = [\text{A}^-]$ and pH = $pK_a$. Equal concentrations provide optimal neutralization for both directions.
When $[\text{HA}] = [\text{A}^-]$ and pH = $pK_a$. Equal concentrations provide optimal neutralization for both directions.
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How is the $pK_a$ of a buffer related to its effective pH range?
How is the $pK_a$ of a buffer related to its effective pH range?
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The effective range is $pK_a \pm 1$. Buffers work within one pH unit of their $pK_a$.
The effective range is $pK_a \pm 1$. Buffers work within one pH unit of their $pK_a$.
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What does the term 'buffer action' refer to?
What does the term 'buffer action' refer to?
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The ability of a buffer to resist pH change. Describes the mechanism by which buffers maintain pH.
The ability of a buffer to resist pH change. Describes the mechanism by which buffers maintain pH.
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How does temperature affect buffer pH?
How does temperature affect buffer pH?
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Temperature can affect the dissociation of the acid/base, altering pH. Temperature changes $K_a$ values, shifting equilibrium.
Temperature can affect the dissociation of the acid/base, altering pH. Temperature changes $K_a$ values, shifting equilibrium.
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What happens to buffer effectiveness when $[\text{HA}]$ and $[\text{A}^-]$ are equal?
What happens to buffer effectiveness when $[\text{HA}]$ and $[\text{A}^-]$ are equal?
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The buffer is most effective; pH = $pK_a$. Equal concentrations optimize both acid and base neutralization.
The buffer is most effective; pH = $pK_a$. Equal concentrations optimize both acid and base neutralization.
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What is the relationship between buffer concentration and buffer capacity?
What is the relationship between buffer concentration and buffer capacity?
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Higher concentrations increase buffer capacity. More buffer molecules available for neutralization reactions.
Higher concentrations increase buffer capacity. More buffer molecules available for neutralization reactions.
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What components make up a typical buffer solution?
What components make up a typical buffer solution?
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A weak acid and its conjugate base, or a weak base and its conjugate acid. The pair must have weak acid/base relationship for buffering action.
A weak acid and its conjugate base, or a weak base and its conjugate acid. The pair must have weak acid/base relationship for buffering action.
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Calculate the pH of a buffer with $[\text{HA}] = 0.20$ M, $[\text{A}^-] = 0.05$ M, $pK_a = 4.75$.
Calculate the pH of a buffer with $[\text{HA}] = 0.20$ M, $[\text{A}^-] = 0.05$ M, $pK_a = 4.75$.
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pH = 4.15. Using Henderson-Hasselbalch: pH = 4.75 + log(0.05/0.20).
pH = 4.15. Using Henderson-Hasselbalch: pH = 4.75 + log(0.05/0.20).
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What happens to buffer effectiveness when $[\text{HA}]$ and $[\text{A}^-]$ are equal?
What happens to buffer effectiveness when $[\text{HA}]$ and $[\text{A}^-]$ are equal?
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The buffer is most effective; pH = $pK_a$. Equal concentrations optimize both acid and base neutralization.
The buffer is most effective; pH = $pK_a$. Equal concentrations optimize both acid and base neutralization.
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Identify the weak acid in the buffer: NH₄Cl/NH₃.
Identify the weak acid in the buffer: NH₄Cl/NH₃.
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NH₄^+$ (ammonium ion). NH₄⁺ donates protons as the weak acid component.
NH₄^+$ (ammonium ion). NH₄⁺ donates protons as the weak acid component.
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What is the pH of a solution with $[\text{HA}] = [\text{A}^-]$ and $pK_a = 5.00$?
What is the pH of a solution with $[\text{HA}] = [\text{A}^-]$ and $pK_a = 5.00$?
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pH = 5.00. When concentrations are equal, pH equals $pK_a$ exactly.
pH = 5.00. When concentrations are equal, pH equals $pK_a$ exactly.
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Identify the role of the conjugate base in a buffer.
Identify the role of the conjugate base in a buffer.
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The conjugate base neutralizes added acids. A⁻ reacts with H⁺ to prevent pH decrease.
The conjugate base neutralizes added acids. A⁻ reacts with H⁺ to prevent pH decrease.
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Determine the pH change when 0.01 M HCl is added to 1 M acetate buffer.
Determine the pH change when 0.01 M HCl is added to 1 M acetate buffer.
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Minimal pH change; buffer resists pH change. High buffer concentration overwhelms the small acid addition.
Minimal pH change; buffer resists pH change. High buffer concentration overwhelms the small acid addition.
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Find the pH of a buffer with $pK_a = 5.00$, $[\text{HA}] = 0.05$ M, $[\text{A}^-] = 0.10$ M.
Find the pH of a buffer with $pK_a = 5.00$, $[\text{HA}] = 0.05$ M, $[\text{A}^-] = 0.10$ M.
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pH = 5.30. Using Henderson-Hasselbalch: pH = 5.00 + log(0.10/0.05).
pH = 5.30. Using Henderson-Hasselbalch: pH = 5.00 + log(0.10/0.05).
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Which buffer component neutralizes added H⁺ ions?
Which buffer component neutralizes added H⁺ ions?
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The conjugate base of the buffer. A⁻ accepts protons from added acid.
The conjugate base of the buffer. A⁻ accepts protons from added acid.
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Why are buffers important in biochemical systems?
Why are buffers important in biochemical systems?
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They maintain stable pH, crucial for enzyme activity. Enzymes require specific pH ranges for optimal activity.
They maintain stable pH, crucial for enzyme activity. Enzymes require specific pH ranges for optimal activity.
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How does a buffer maintain a nearly constant pH?
How does a buffer maintain a nearly constant pH?
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By neutralizing added acids or bases with its components. Weak acid/base equilibrium maintains constant H⁺ concentration.
By neutralizing added acids or bases with its components. Weak acid/base equilibrium maintains constant H⁺ concentration.
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Calculate the pH of a buffer with $[\text{HA}] = 0.10$ M, $[\text{A}^-] = 0.10$ M, $pK_a = 4.75$.
Calculate the pH of a buffer with $[\text{HA}] = 0.10$ M, $[\text{A}^-] = 0.10$ M, $pK_a = 4.75$.
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pH = 4.75. Equal concentrations make log term zero, so pH = $pK_a$.
pH = 4.75. Equal concentrations make log term zero, so pH = $pK_a$.
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What effect does adding a strong base have on a buffer?
What effect does adding a strong base have on a buffer?
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The buffer neutralizes it, minimizing pH change. Weak acid consumes OH⁻, preventing pH rise.
The buffer neutralizes it, minimizing pH change. Weak acid consumes OH⁻, preventing pH rise.
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Which solution is a buffer: NaOH/NaCl or NH₄Cl/NH₃?
Which solution is a buffer: NaOH/NaCl or NH₄Cl/NH₃?
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NH₄Cl/NH₃. NH₄⁺/NH₃ is a weak acid/base pair; NaOH/NaCl is not.
NH₄Cl/NH₃. NH₄⁺/NH₃ is a weak acid/base pair; NaOH/NaCl is not.
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How does a buffer solution differ from a neutral solution?
How does a buffer solution differ from a neutral solution?
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A buffer resists pH changes; a neutral solution does not. Buffers actively resist pH change through chemical equilibrium.
A buffer resists pH changes; a neutral solution does not. Buffers actively resist pH change through chemical equilibrium.
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What is the primary purpose of a buffer solution?
What is the primary purpose of a buffer solution?
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To resist changes in pH upon addition of small amounts of acid or base. Buffers maintain pH stability through weak acid/base equilibrium.
To resist changes in pH upon addition of small amounts of acid or base. Buffers maintain pH stability through weak acid/base equilibrium.
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Choose the buffer pair: HCl/NaCl or CH₃COOH/CH₃COONa?
Choose the buffer pair: HCl/NaCl or CH₃COOH/CH₃COONa?
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CH₃COOH/CH₃COONa. Acetic acid is weak; HCl is strong and cannot buffer.
CH₃COOH/CH₃COONa. Acetic acid is weak; HCl is strong and cannot buffer.
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Identify the role of the weak acid in a buffer.
Identify the role of the weak acid in a buffer.
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The weak acid neutralizes added bases. HA reacts with OH⁻ to prevent pH increase.
The weak acid neutralizes added bases. HA reacts with OH⁻ to prevent pH increase.
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Which property of a buffer determines its capacity?
Which property of a buffer determines its capacity?
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The concentrations of the acid and conjugate base. Higher concentrations provide more buffering molecules.
The concentrations of the acid and conjugate base. Higher concentrations provide more buffering molecules.
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What is the effect of dilution on buffer capacity?
What is the effect of dilution on buffer capacity?
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Dilution decreases buffer capacity. Fewer buffer molecules means less neutralization ability.
Dilution decreases buffer capacity. Fewer buffer molecules means less neutralization ability.
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What is the effect of adding a salt of the weak acid to a buffer?
What is the effect of adding a salt of the weak acid to a buffer?
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It increases buffer capacity. More conjugate base increases neutralization ability.
It increases buffer capacity. More conjugate base increases neutralization ability.
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Which property is enhanced by equal concentrations of buffer components?
Which property is enhanced by equal concentrations of buffer components?
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Buffer capacity is maximized. Equal amounts optimize neutralization in both directions.
Buffer capacity is maximized. Equal amounts optimize neutralization in both directions.
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