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: 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 7: 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 8: Which buffer component neutralizes added OH⁻ ions?

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

Flashcard 9: 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 10: 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 11: 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 12: Which property is enhanced by equal concentrations of buffer components?

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

Flashcard 13: 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 14: Which property of a buffer determines its capacity?

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

Flashcard 15: 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 16: 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 17: 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 18: 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 19: 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 20: 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 21: 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 22: Identify a real-world application of buffers.

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

Flashcard 23: 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 24: 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 25: 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 26: 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 27: 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 28: 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 29: 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 30: Which buffer component neutralizes added H⁺ ions?

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

Flashcard 31: Which buffer component neutralizes added H⁺ ions?

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

Flashcard 32: 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 33: 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 34: 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 35: 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 36: Identify the weak acid in the buffer: NH₄Cl/NH₃.

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

Flashcard 37: 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 38: 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 39: Which property is enhanced by equal concentrations of buffer components?

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

Flashcard 40: 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 41: Which buffer component neutralizes added H⁺ ions?

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

Flashcard 42: 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 43: 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 44: 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 45: Identify the weak acid in the buffer: NH₄Cl/NH₃.

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

Flashcard 46: Which property is enhanced by equal concentrations of buffer components?

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

Flashcard 47: 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 48: What is the effect of dilution on buffer capacity?

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

Flashcard 49: 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 50: 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 51: Identify a real-world application of buffers.

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

Flashcard 52: Which buffer component neutralizes added OH⁻ ions?

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

Flashcard 53: 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 54: 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 55: 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 56: What is the relationship between buffer concentration and buffer capacity?

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

Flashcard 57: 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 58: 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 59: 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 60: 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 61: 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 62: 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 63: Choose the buffer pair: HCl/NaCl or CH₃COOH/CH₃COONa?

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

Flashcard 64: What is the relationship between buffer concentration and buffer capacity?

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

Flashcard 65: 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 66: 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 67: 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 68: 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 69: 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 70: 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 71: 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 72: Which property of a buffer determines its capacity?

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

Flashcard 73: 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 74: 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 75: Which property is enhanced by equal concentrations of buffer components?

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

Flashcard 76: 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 77: 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 78: 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 79: 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 80: 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 81: 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 82: 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 83: 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 84: 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 85: 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 86: 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 87: Choose the buffer pair: HCl/NaCl or CH₃COOH/CH₃COONa?

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

Flashcard 88: 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 89: 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 90: 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 91: 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 92: What is the relationship between buffer concentration and buffer capacity?

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

Flashcard 93: 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 94: 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 95: 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 96: Identify the weak acid in the buffer: NH₄Cl/NH₃.

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

Flashcard 97: 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 98: 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 99: Which buffer component neutralizes added H⁺ ions?

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

Flashcard 100: Which property of a buffer determines its capacity?

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