AP Chemistry Flashcards: Properties Of Buffers

What this deck covers

This deck focuses on Properties Of Buffers, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Which solution is a buffer: NaOH/NaCl or NH₄Cl/NH₃?

Answer: NH₄Cl/NH₃. NH₄⁺/NH₃ is a weak acid/base pair; NaOH/NaCl is not.

Flashcard 2: What is the relation between $K_a$ and buffer strength?

Answer: Larger $K_a$ values indicate stronger acids, affecting buffer strength. $K_a$ determines $pK_a$, which sets the optimal pH range.

Flashcard 3: Calculate the pH of a buffer with $[\text{HA}] = 0.10$ M, $[\text{A}^-] = 0.10$ M, $pK_a = 4.75$.

Answer: pH = 4.75. Equal concentrations make log term zero, so pH = $pK_a$.

Flashcard 4: Identify the role of the conjugate base in a buffer.

Answer: The conjugate base neutralizes added acids. A⁻ reacts with H⁺ to prevent pH decrease.

Flashcard 5: Determine the pH of a buffer: $pK_a = 4.76$, $[\text{HA}] = 0.1$ M, $[\text{A}^-] = 0.1$ M.

Answer: pH = 4.76. Equal concentrations make the log term zero.

Flashcard 6: Calculate the pH of a buffer with $[\text{HA}] = 0.10$ M, $[\text{A}^-] = 0.10$ M, $pK_a = 4.75$.

Answer: pH = 4.75. Equal concentrations make log term zero, so pH = $pK_a$.

Flashcard 7: Which buffer component neutralizes added OH⁻ ions?

Answer: The weak acid of the buffer. HA donates protons to neutralize added base.

Flashcard 8: What does the term 'buffer action' refer to?

Answer: The ability of a buffer to resist pH change. Describes the mechanism by which buffers maintain pH.

Flashcard 9: What effect does adding a strong base have on a buffer?

Answer: The buffer neutralizes it, minimizing pH change. Weak acid consumes OH⁻, preventing pH rise.

Flashcard 10: What components make up a typical buffer solution?

Answer: 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.

Flashcard 11: Which property of a buffer determines its capacity?

Answer: The concentrations of the acid and conjugate base. Higher concentrations provide more buffering molecules.

Flashcard 12: What is the maximum buffer capacity condition?

Answer: When $[\text{HA}] = [\text{A}^-]$ and pH = $pK_a$. Equal concentrations provide optimal neutralization for both directions.

Flashcard 13: What does the term 'buffer action' refer to?

Answer: The ability of a buffer to resist pH change. Describes the mechanism by which buffers maintain pH.

Flashcard 14: What is the effect of adding a salt of the weak acid to a buffer?

Answer: It increases buffer capacity. More conjugate base increases neutralization ability.

Flashcard 15: What is the pH of a solution with $[\text{HA}] = [\text{A}^-]$ and $pK_a = 5.00$?

Answer: pH = 5.00. When concentrations are equal, pH equals $pK_a$ exactly.

Flashcard 16: How is the $pK_a$ of a buffer related to its effective pH range?

Answer: The effective range is $pK_a \pm 1$. Buffers work within one pH unit of their $pK_a$.

Flashcard 17: What is the primary purpose of a buffer solution?

Answer: To resist changes in pH upon addition of small amounts of acid or base. Buffers maintain pH stability through weak acid/base equilibrium.

Flashcard 18: What is the effect of adding water to a buffer solution?

Answer: Dilution reduces buffer capacity but does not significantly change pH. Dilution affects capacity but concentration ratio remains constant.

Flashcard 19: What is the effect of adding water to a buffer solution?

Answer: Dilution reduces buffer capacity but does not significantly change pH. Dilution affects capacity but concentration ratio remains constant.

Flashcard 20: Find the pH of a buffer with $pK_a = 5.00$, $[\text{HA}] = 0.05$ M, $[\text{A}^-] = 0.10$ M.

Answer: pH = 5.30. Using Henderson-Hasselbalch: pH = 5.00 + log(0.10/0.05).

Flashcard 21: What is the pH of a buffer if $pK_a = 6.5$ and $[\text{A}^-]/[\text{HA}] = 10$?

Answer: pH = 7.5. Using Henderson-Hasselbalch: pH = 6.5 + log(10) = 7.5.

Flashcard 22: What is the primary purpose of a buffer solution?

Answer: To resist changes in pH upon addition of small amounts of acid or base. Buffers maintain pH stability through weak acid/base equilibrium.

Flashcard 23: In what pH range does an acetic acid/sodium acetate buffer work best?

Answer: pH 3.74 to 5.74. Acetic acid has $pK_a$ = 4.74, so range is 3.74-5.74.

Flashcard 24: What is the optimal pH range of a buffer in relation to its $pK_a$?

Answer: Within 1 pH unit above or below $pK_a$. Buffer works best when pH is close to its $pK_a$ value.

Flashcard 25: Which buffer component neutralizes added H⁺ ions?

Answer: The conjugate base of the buffer. A⁻ accepts protons from added acid.

Flashcard 26: Why are buffers important in biochemical systems?

Answer: They maintain stable pH, crucial for enzyme activity. Enzymes require specific pH ranges for optimal activity.

Flashcard 27: What is the buffer capacity?

Answer: The amount of acid or base a buffer can neutralize before pH changes significantly. Measures how much acid/base can be added before breakdown.

Flashcard 28: How does temperature affect buffer pH?

Answer: Temperature can affect the dissociation of the acid/base, altering pH. Temperature changes $K_a$ values, shifting equilibrium.

Flashcard 29: Determine the pH of a buffer: $pK_a = 4.76$, $[\text{HA}] = 0.1$ M, $[\text{A}^-] = 0.1$ M.

Answer: pH = 4.76. Equal concentrations make the log term zero.

Flashcard 30: Identify the weak acid in the buffer: NH₄Cl/NH₃.

Answer: NH₄^+$ (ammonium ion). NH₄⁺ donates protons as the weak acid component.

Flashcard 31: Which property is enhanced by equal concentrations of buffer components?

Answer: Buffer capacity is maximized. Equal amounts optimize neutralization in both directions.

Flashcard 32: Which buffer component neutralizes added H⁺ ions?

Answer: The conjugate base of the buffer. A⁻ accepts protons from added acid.

Flashcard 33: What effect does adding a strong base have on a buffer?

Answer: The buffer neutralizes it, minimizing pH change. Weak acid consumes OH⁻, preventing pH rise.

Flashcard 34: What is the effect of adding a salt of the weak acid to a buffer?

Answer: It increases buffer capacity. More conjugate base increases neutralization ability.

Flashcard 35: Which property is enhanced by equal concentrations of buffer components?

Answer: Buffer capacity is maximized. Equal amounts optimize neutralization in both directions.

Flashcard 36: How does a buffer maintain a nearly constant pH?

Answer: By neutralizing added acids or bases with its components. Weak acid/base equilibrium maintains constant H⁺ concentration.

Flashcard 37: Calculate the pH of a buffer with $[\text{HA}] = 0.20$ M, $[\text{A}^-] = 0.05$ M, $pK_a = 4.75$.

Answer: pH = 4.15. Using Henderson-Hasselbalch: pH = 4.75 + log(0.05/0.20).

Flashcard 38: Identify the role of the weak acid in a buffer.

Answer: The weak acid neutralizes added bases. HA reacts with OH⁻ to prevent pH increase.

Flashcard 39: Identify a real-world application of buffers.

Answer: Blood pH regulation. Maintains physiological pH around 7.4 for proper function.

Flashcard 40: Which buffer component neutralizes added OH⁻ ions?

Answer: The weak acid of the buffer. HA donates protons to neutralize added base.

Flashcard 41: Identify the role of the conjugate base in a buffer.

Answer: The conjugate base neutralizes added acids. A⁻ reacts with H⁺ to prevent pH decrease.

Flashcard 42: How does a buffer solution differ from a neutral solution?

Answer: A buffer resists pH changes; a neutral solution does not. Buffers actively resist pH change through chemical equilibrium.

Flashcard 43: What is the relationship between buffer concentration and buffer capacity?

Answer: Higher concentrations increase buffer capacity. More buffer molecules available for neutralization reactions.

Flashcard 44: Identify the role of the weak acid in a buffer.

Answer: The weak acid neutralizes added bases. HA reacts with OH⁻ to prevent pH increase.

Flashcard 45: How does temperature affect buffer pH?

Answer: Temperature can affect the dissociation of the acid/base, altering pH. Temperature changes $K_a$ values, shifting equilibrium.

Flashcard 46: What is the pH of a solution with $[\text{HA}] = [\text{A}^-]$ and $pK_a = 5.00$?

Answer: pH = 5.00. When concentrations are equal, pH equals $pK_a$ exactly.

Flashcard 47: How is the $pK_a$ of a buffer related to its effective pH range?

Answer: The effective range is $pK_a \pm 1$. Buffers work within one pH unit of their $pK_a$.

Flashcard 48: Which solution is a buffer: NaOH/NaCl or NH₄Cl/NH₃?

Answer: NH₄Cl/NH₃. NH₄⁺/NH₃ is a weak acid/base pair; NaOH/NaCl is not.

Flashcard 49: Choose the buffer pair: HCl/NaCl or CH₃COOH/CH₃COONa?

Answer: CH₃COOH/CH₃COONa. Acetic acid is weak; HCl is strong and cannot buffer.

Flashcard 50: What is the relationship between buffer concentration and buffer capacity?

Answer: Higher concentrations increase buffer capacity. More buffer molecules available for neutralization reactions.

Flashcard 51: What is the primary purpose of a buffer solution?

Answer: To resist changes in pH upon addition of small amounts of acid or base. Buffers maintain pH stability through weak acid/base equilibrium.

Flashcard 52: In what pH range does an acetic acid/sodium acetate buffer work best?

Answer: pH 3.74 to 5.74. Acetic acid has $pK_a$ = 4.74, so range is 3.74-5.74.

Flashcard 53: What is the optimal pH range of a buffer in relation to its $pK_a$?

Answer: Within 1 pH unit above or below $pK_a$. Buffer works best when pH is close to its $pK_a$ value.

Flashcard 54: What effect does adding a strong acid have on a buffer?

Answer: The buffer neutralizes it, minimizing pH change. Conjugate base consumes H⁺, preventing pH drop.

Flashcard 55: Determine the pH change when 0.01 M HCl is added to 1 M acetate buffer.

Answer: Minimal pH change; buffer resists pH change. High buffer concentration overwhelms the small acid addition.

Flashcard 56: Determine the pH change when 0.01 M HCl is added to 1 M acetate buffer.

Answer: Minimal pH change; buffer resists pH change. High buffer concentration overwhelms the small acid addition.

Flashcard 57: Which property of a buffer determines its capacity?

Answer: The concentrations of the acid and conjugate base. Higher concentrations provide more buffering molecules.

Flashcard 58: What is the relation between $K_a$ and buffer strength?

Answer: Larger $K_a$ values indicate stronger acids, affecting buffer strength. $K_a$ determines $pK_a$, which sets the optimal pH range.

Flashcard 59: How does a buffer solution differ from a neutral solution?

Answer: A buffer resists pH changes; a neutral solution does not. Buffers actively resist pH change through chemical equilibrium.

Flashcard 60: Which property is enhanced by equal concentrations of buffer components?

Answer: Buffer capacity is maximized. Equal amounts optimize neutralization in both directions.

Flashcard 61: What happens to buffer effectiveness when $[\text{HA}]$ and $[\text{A}^-]$ are equal?

Answer: The buffer is most effective; pH = $pK_a$. Equal concentrations optimize both acid and base neutralization.

Flashcard 62: What effect does adding a strong acid have on a buffer?

Answer: The buffer neutralizes it, minimizing pH change. Conjugate base consumes H⁺, preventing pH drop.

Flashcard 63: What is the relation between $K_a$ and buffer strength?

Answer: Larger $K_a$ values indicate stronger acids, affecting buffer strength. $K_a$ determines $pK_a$, which sets the optimal pH range.

Flashcard 64: Identify the role of the weak acid in a buffer.

Answer: The weak acid neutralizes added bases. HA reacts with OH⁻ to prevent pH increase.

Flashcard 65: What happens to buffer effectiveness when $[\text{HA}]$ and $[\text{A}^-]$ are equal?

Answer: The buffer is most effective; pH = $pK_a$. Equal concentrations optimize both acid and base neutralization.

Flashcard 66: How does a buffer maintain a nearly constant pH?

Answer: By neutralizing added acids or bases with its components. Weak acid/base equilibrium maintains constant H⁺ concentration.

Flashcard 67: Choose the buffer pair: HCl/NaCl or CH₃COOH/CH₃COONa?

Answer: CH₃COOH/CH₃COONa. Acetic acid is weak; HCl is strong and cannot buffer.

Flashcard 68: Find the pH of a buffer with $pK_a = 5.00$, $[\text{HA}] = 0.05$ M, $[\text{A}^-] = 0.10$ M.

Answer: pH = 5.30. Using Henderson-Hasselbalch: pH = 5.00 + log(0.10/0.05).

Flashcard 69: How does a buffer maintain a nearly constant pH?

Answer: By neutralizing added acids or bases with its components. Weak acid/base equilibrium maintains constant H⁺ concentration.

Flashcard 70: What happens to buffer effectiveness when $[\text{HA}]$ and $[\text{A}^-]$ are equal?

Answer: The buffer is most effective; pH = $pK_a$. Equal concentrations optimize both acid and base neutralization.

Flashcard 71: What is the relationship between buffer concentration and buffer capacity?

Answer: Higher concentrations increase buffer capacity. More buffer molecules available for neutralization reactions.

Flashcard 72: In what pH range does an acetic acid/sodium acetate buffer work best?

Answer: pH 3.74 to 5.74. Acetic acid has $pK_a$ = 4.74, so range is 3.74-5.74.

Flashcard 73: What is the pH of a buffer if $pK_a = 6.5$ and $[\text{A}^-]/[\text{HA}] = 10$?

Answer: pH = 7.5. Using Henderson-Hasselbalch: pH = 6.5 + log(10) = 7.5.

Flashcard 74: Identify the weak acid in the buffer: NH₄Cl/NH₃.

Answer: NH₄^+$ (ammonium ion). NH₄⁺ donates protons as the weak acid component.

Flashcard 75: Calculate the pH of a buffer with $[\text{HA}] = 0.20$ M, $[\text{A}^-] = 0.05$ M, $pK_a = 4.75$.

Answer: pH = 4.15. Using Henderson-Hasselbalch: pH = 4.75 + log(0.05/0.20).

Flashcard 76: How is the $pK_a$ of a buffer related to its effective pH range?

Answer: The effective range is $pK_a \pm 1$. Buffers work within one pH unit of their $pK_a$.

Flashcard 77: Which buffer component neutralizes added H⁺ ions?

Answer: The conjugate base of the buffer. A⁻ accepts protons from added acid.

Flashcard 78: Identify a real-world application of buffers.

Answer: Blood pH regulation. Maintains physiological pH around 7.4 for proper function.

Flashcard 79: What is the buffer capacity?

Answer: The amount of acid or base a buffer can neutralize before pH changes significantly. Measures how much acid/base can be added before breakdown.

Flashcard 80: Which property of a buffer determines its capacity?

Answer: The concentrations of the acid and conjugate base. Higher concentrations provide more buffering molecules.

Flashcard 81: What is the effect of dilution on buffer capacity?

Answer: Dilution decreases buffer capacity. Fewer buffer molecules means less neutralization ability.

Flashcard 82: Which factors do not affect the pH of a buffer?

Answer: The absolute concentrations of the buffer components. pH depends only on the concentration ratio, not individual amounts.

Flashcard 83: What is the buffer capacity?

Answer: The amount of acid or base a buffer can neutralize before pH changes significantly. Measures how much acid/base can be added before breakdown.

Flashcard 84: What effect does adding a strong base have on a buffer?

Answer: The buffer neutralizes it, minimizing pH change. Weak acid consumes OH⁻, preventing pH rise.

Flashcard 85: What components make up a typical buffer solution?

Answer: 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.

Flashcard 86: Identify the role of the conjugate base in a buffer.

Answer: The conjugate base neutralizes added acids. A⁻ reacts with H⁺ to prevent pH decrease.

Flashcard 87: Determine the pH change when 0.01 M HCl is added to 1 M acetate buffer.

Answer: Minimal pH change; buffer resists pH change. High buffer concentration overwhelms the small acid addition.

Flashcard 88: What is the effect of adding water to a buffer solution?

Answer: Dilution reduces buffer capacity but does not significantly change pH. Dilution affects capacity but concentration ratio remains constant.

Flashcard 89: What is the effect of adding a salt of the weak acid to a buffer?

Answer: It increases buffer capacity. More conjugate base increases neutralization ability.

Flashcard 90: What is the maximum buffer capacity condition?

Answer: When $[\text{HA}] = [\text{A}^-]$ and pH = $pK_a$. Equal concentrations provide optimal neutralization for both directions.

Flashcard 91: What does the term 'buffer action' refer to?

Answer: The ability of a buffer to resist pH change. Describes the mechanism by which buffers maintain pH.

Flashcard 92: Identify the weak acid in the buffer: NH₄Cl/NH₃.

Answer: NH₄^+$ (ammonium ion). NH₄⁺ donates protons as the weak acid component.

Flashcard 93: What is the pH of a solution with $[\text{HA}] = [\text{A}^-]$ and $pK_a = 5.00$?

Answer: pH = 5.00. When concentrations are equal, pH equals $pK_a$ exactly.

Flashcard 94: What is the optimal pH range of a buffer in relation to its $pK_a$?

Answer: Within 1 pH unit above or below $pK_a$. Buffer works best when pH is close to its $pK_a$ value.

Flashcard 95: What is the effect of dilution on buffer capacity?

Answer: Dilution decreases buffer capacity. Fewer buffer molecules means less neutralization ability.

Flashcard 96: What is the maximum buffer capacity condition?

Answer: When $[\text{HA}] = [\text{A}^-]$ and pH = $pK_a$. Equal concentrations provide optimal neutralization for both directions.

Flashcard 97: Which factors do not affect the pH of a buffer?

Answer: The absolute concentrations of the buffer components. pH depends only on the concentration ratio, not individual amounts.

Flashcard 98: Why are buffers important in biochemical systems?

Answer: They maintain stable pH, crucial for enzyme activity. Enzymes require specific pH ranges for optimal activity.

Flashcard 99: Which buffer component neutralizes added OH⁻ ions?

Answer: The weak acid of the buffer. HA donates protons to neutralize added base.

Flashcard 100: Which factors do not affect the pH of a buffer?

Answer: The absolute concentrations of the buffer components. pH depends only on the concentration ratio, not individual amounts.