AP Chemistry Flashcards: Buffer Capacity

What this deck covers

This deck focuses on Buffer Capacity, 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: What is the significance of the pKa value in buffers?

Answer: pKa indicates the pH at which a buffer is most effective. Buffer capacity is maximized when solution pH equals the acid's $\text{p}K_a$.

Flashcard 2: What is the effect of a strong acid on a weak acid buffer?

Answer: It can decrease the buffer's capacity rapidly. Strong acid consumes conjugate base, reducing the buffer's effectiveness.

Flashcard 3: What is the role of buffers in biological systems?

Answer: Buffers maintain stable pH for biological processes. Essential for enzyme function, cellular processes, and metabolic reactions.

Flashcard 4: What is a buffer's response to added acid or base?

Answer: A buffer resists pH changes. Weak acid neutralizes added base; conjugate base neutralizes added acid.

Flashcard 5: Find the buffer capacity: 0.1 mol base changes pH by 0.2.

Answer: Buffer capacity = 0.1/0.2 = 0.5. Standard application of the buffer capacity formula.

Flashcard 6: How does the ratio of buffer components affect buffer capacity?

Answer: A 1:1 ratio of acid to conjugate base maximizes buffer capacity. Equal amounts provide optimal resistance to pH changes in both directions.

Flashcard 7: What is the buffer capacity if 0.05 mol of NaOH causes a pH change of 0.1?

Answer: Buffer capacity = 0.05/0.1 = 0.5. Applying the definition: capacity = moles added divided by pH change.

Flashcard 8: What is the effect of increasing buffer concentration on buffer capacity?

Answer: Increasing concentration increases buffer capacity. More buffer molecules available to neutralize added acids or bases.

Flashcard 9: What is the definition of buffer capacity?

Answer: Buffer capacity is the ability of a buffer to resist changes in pH. Quantifies how well buffers maintain stable pH when acids or bases are added.

Flashcard 10: Identify the formula for calculating buffer capacity.

Answer: Buffer capacity = Δn/ΔpH. Where $\Delta n$ is moles added and $\Delta pH$ is the resulting pH change.

Flashcard 11: How does dilution affect buffer capacity?

Answer: Dilution decreases buffer capacity. Lower concentrations mean fewer buffer molecules to resist pH changes.

Flashcard 12: How is buffer capacity related to the Henderson-Hasselbalch equation?

Answer: It helps determine the pH range where buffer capacity is effective. Shows optimal buffering occurs when pH = $\text{p}K_a$ and ratio is 1:1.

Flashcard 13: What determines the effective pH range of a buffer?

Answer: The pKa of the acid and the concentration ratio. Buffer works best within $\text{p}K_a \pm 1$ pH unit range.

Flashcard 14: How does the ratio of buffer components affect buffer capacity?

Answer: A 1:1 ratio of acid to conjugate base maximizes buffer capacity. Equal amounts provide optimal resistance to pH changes in both directions.

Flashcard 15: What is the role of buffers in biological systems?

Answer: Buffers maintain stable pH for biological processes. Essential for enzyme function, cellular processes, and metabolic reactions.

Flashcard 16: Calculate the buffer capacity: 0.02 mol base changes pH by 0.04.

Answer: Buffer capacity = 0.02/0.04 = 0.5. Standard buffer capacity calculation using the defining formula.

Flashcard 17: Why is a 1:1 ratio of acid to conjugate base optimal for buffering?

Answer: It maximizes buffer capacity by keeping pH near pKa. When concentrations are equal, pH equals $\text{p}K_a$ for maximum effectiveness.

Flashcard 18: Find the pH change if 0.01 mol of HCl is added to a buffer with capacity 0.2.

Answer: ΔpH = 0.01/0.2 = 0.05. Using buffer capacity formula: $\Delta pH = \Delta n \div \text{capacity}$.

Flashcard 19: How is buffer capacity related to the Henderson-Hasselbalch equation?

Answer: It helps determine the pH range where buffer capacity is effective. Shows optimal buffering occurs when pH = $\text{p}K_a$ and ratio is 1:1.

Flashcard 20: Choose the correct statement about strong acids and buffers.

Answer: Strong acids can overwhelm buffers, reducing capacity. Adding excess strong acid depletes the conjugate base component.

Flashcard 21: Identify a situation where buffer capacity is crucial.

Answer: In biochemical reactions requiring specific pH. Enzyme catalysis, protein folding, and cellular metabolism require stable pH.

Flashcard 22: How is buffer capacity measured experimentally?

Answer: By titration with a strong acid or base. Gradual addition while monitoring pH change determines buffering ability.

Flashcard 23: How does pH affect enzyme activity in buffered solutions?

Answer: Buffers maintain optimal pH for enzyme activity. Enzymes require specific pH ranges for proper folding and catalytic activity.

Flashcard 24: How does the presence of a buffer affect a titration curve?

Answer: It flattens the curve within the buffer range. Creates a flat region where pH changes slowly with added titrant.

Flashcard 25: Identify the formula for calculating buffer capacity.

Answer: Buffer capacity = Δn/ΔpH. Where $\Delta n$ is moles added and $\Delta pH$ is the resulting pH change.

Flashcard 26: What is the role of a buffer in a solution?

Answer: A buffer maintains a stable pH in a solution. Neutralizes added acids or bases to prevent large pH changes.

Flashcard 27: Calculate buffer capacity: 0.05 mol acid causes pH change of 0.25.

Answer: Buffer capacity = 0.05/0.25 = 0.2. Direct calculation using capacity = moles added / pH change.

Flashcard 28: Calculate the buffer capacity: 0.02 mol base changes pH by 0.04.

Answer: Buffer capacity = 0.02/0.04 = 0.5. Standard buffer capacity calculation using the defining formula.

Flashcard 29: Choose the correct statement about strong acids and buffers.

Answer: Strong acids can overwhelm buffers, reducing capacity. Adding excess strong acid depletes the conjugate base component.

Flashcard 30: What happens to buffer capacity when the pH is far from pKa?

Answer: Buffer capacity decreases. Maximum capacity occurs when pH equals $\text{p}K_a$ of the buffer system.

Flashcard 31: What happens to buffer capacity when the pH is far from pKa?

Answer: Buffer capacity decreases. Maximum capacity occurs when pH equals $\text{p}K_a$ of the buffer system.

Flashcard 32: Identify the primary buffer system in human blood.

Answer: The bicarbonate buffer system. $\text{HCO}_3^- / \text{H}_2\text{CO}_3$ system maintains blood pH around 7.4.

Flashcard 33: What is the buffer capacity if 0.05 mol of NaOH causes a pH change of 0.1?

Answer: Buffer capacity = 0.05/0.1 = 0.5. Applying the definition: capacity = moles added divided by pH change.

Flashcard 34: Identify a situation where buffer capacity is crucial.

Answer: In biochemical reactions requiring specific pH. Enzyme catalysis, protein folding, and cellular metabolism require stable pH.

Flashcard 35: Identify the primary function of a buffer in a titration.

Answer: To stabilize pH changes near the equivalence point. Buffers prevent sharp pH changes during acid-base neutralization reactions.

Flashcard 36: How does the presence of a buffer affect a titration curve?

Answer: It flattens the curve within the buffer range. Creates a flat region where pH changes slowly with added titrant.

Flashcard 37: What is the optimal pH range for a buffer with pKa of 4.75?

Answer: Optimal pH range: 3.75 to 5.75. Effective buffering range is $\text{p}K_a \pm 1$ pH unit.

Flashcard 38: Identify the primary buffer system in human blood.

Answer: The bicarbonate buffer system. $\text{HCO}_3^- / \text{H}_2\text{CO}_3$ system maintains blood pH around 7.4.

Flashcard 39: Identify a common laboratory buffer system.

Answer: The phosphate buffer system. $\text{HPO}_4^{2-} / \text{H}_2\text{PO}_4^-$ system with $\text{p}K_a$ of 7.2.

Flashcard 40: What is the relationship between buffer capacity and buffer range?

Answer: Buffer capacity is highest within the buffer range. Buffer range ($\text{p}K_a \pm 1$) defines where capacity is most effective.

Flashcard 41: Which factors affect buffer capacity?

Answer: Concentration of buffer components and their ratio. Higher concentrations and equal ratios provide maximum buffering effectiveness.

Flashcard 42: What is the significance of the pKa value in buffers?

Answer: pKa indicates the pH at which a buffer is most effective. Buffer capacity is maximized when solution pH equals the acid's $\text{p}K_a$.

Flashcard 43: How does temperature affect buffer capacity?

Answer: Temperature can affect dissociation and thus buffer capacity. Higher temperatures increase ionization, affecting buffer equilibrium.

Flashcard 44: What is the typical composition of a buffer solution?

Answer: A weak acid and its conjugate base or vice versa. Weak acid/conjugate base pairs resist pH changes when acids or bases are added.

Flashcard 45: What is the effect of increasing buffer concentration on buffer capacity?

Answer: Increasing concentration increases buffer capacity. More buffer molecules available to neutralize added acids or bases.

Flashcard 46: Find the pH change if 0.01 mol of HCl is added to a buffer with capacity 0.2.

Answer: ΔpH = 0.01/0.2 = 0.05. Using buffer capacity formula: $\Delta pH = \Delta n \div \text{capacity}$.

Flashcard 47: What happens to buffer capacity with equal concentrations of acid and base?

Answer: Buffer capacity is maximized. Equal concentrations create optimal conditions for resisting pH changes.

Flashcard 48: Identify the primary function of a buffer in a titration.

Answer: To stabilize pH changes near the equivalence point. Buffers prevent sharp pH changes during acid-base neutralization reactions.

Flashcard 49: What is the optimal pH range for a buffer with pKa of 4.75?

Answer: Optimal pH range: 3.75 to 5.75. Effective buffering range is $\text{p}K_a \pm 1$ pH unit.

Flashcard 50: What is a buffer's response to added acid or base?

Answer: A buffer resists pH changes. Weak acid neutralizes added base; conjugate base neutralizes added acid.

Flashcard 51: Calculate buffer capacity: 0.02 mol of acid changes pH by 0.1.

Answer: Buffer capacity = 0.02/0.1 = 0.2. Direct application of capacity formula: $\Delta n / \Delta pH$.

Flashcard 52: What is the relationship between buffer capacity and buffer range?

Answer: Buffer capacity is highest within the buffer range. Buffer range ($\text{p}K_a \pm 1$) defines where capacity is most effective.

Flashcard 53: What does Δn represent in the buffer capacity formula?

Answer: Δn is the amount of acid or base added. Moles of strong acid or base added to the buffer solution.

Flashcard 54: What is the result of adding a strong base to an acidic buffer?

Answer: The buffer neutralizes the base, maintaining pH. Weak acid component neutralizes the added base to minimize pH change.

Flashcard 55: What is the definition of buffer capacity?

Answer: Buffer capacity is the ability of a buffer to resist changes in pH. Quantifies how well buffers maintain stable pH when acids or bases are added.

Flashcard 56: Calculate pH change: 0.01 mol NaOH in buffer capacity of 0.5.

Answer: ΔpH = 0.01/0.5 = 0.02. Using the buffer capacity equation to find resulting pH change.

Flashcard 57: What is the effect of a strong acid on a weak acid buffer?

Answer: It can decrease the buffer's capacity rapidly. Strong acid consumes conjugate base, reducing the buffer's effectiveness.

Flashcard 58: How does buffer capacity change with pH deviation from pKa?

Answer: It decreases as pH moves away from pKa. Maximum effectiveness occurs at pH = $\text{p}K_a$, declining as pH deviates.

Flashcard 59: Why is a 1:1 ratio of acid to conjugate base optimal for buffering?

Answer: It maximizes buffer capacity by keeping pH near pKa. When concentrations are equal, pH equals $\text{p}K_a$ for maximum effectiveness.

Flashcard 60: What is the role of a buffer in a solution?

Answer: A buffer maintains a stable pH in a solution. Neutralizes added acids or bases to prevent large pH changes.

Flashcard 61: How does temperature affect buffer capacity?

Answer: Temperature can affect dissociation and thus buffer capacity. Higher temperatures increase ionization, affecting buffer equilibrium.

Flashcard 62: How does dilution affect buffer capacity?

Answer: Dilution decreases buffer capacity. Lower concentrations mean fewer buffer molecules to resist pH changes.

Flashcard 63: How is buffer capacity measured experimentally?

Answer: By titration with a strong acid or base. Gradual addition while monitoring pH change determines buffering ability.

Flashcard 64: Calculate buffer capacity: 0.02 mol of acid changes pH by 0.1.

Answer: Buffer capacity = 0.02/0.1 = 0.2. Direct application of capacity formula: $\Delta n / \Delta pH$.

Flashcard 65: What is the typical composition of a buffer solution?

Answer: A weak acid and its conjugate base or vice versa. Weak acid/conjugate base pairs resist pH changes when acids or bases are added.

Flashcard 66: What is the result of adding a strong base to an acidic buffer?

Answer: The buffer neutralizes the base, maintaining pH. Weak acid component neutralizes the added base to minimize pH change.

Flashcard 67: Calculate buffer capacity: 0.05 mol acid causes pH change of 0.25.

Answer: Buffer capacity = 0.05/0.25 = 0.2. Direct calculation using capacity = moles added / pH change.

Flashcard 68: Find the buffer capacity: 0.1 mol base changes pH by 0.2.

Answer: Buffer capacity = 0.1/0.2 = 0.5. Standard application of the buffer capacity formula.

Flashcard 69: What determines the effective pH range of a buffer?

Answer: The pKa of the acid and the concentration ratio. Buffer works best within $\text{p}K_a \pm 1$ pH unit range.

Flashcard 70: Which factors affect buffer capacity?

Answer: Concentration of buffer components and their ratio. Higher concentrations and equal ratios provide maximum buffering effectiveness.

Flashcard 71: How does pH affect enzyme activity in buffered solutions?

Answer: Buffers maintain optimal pH for enzyme activity. Enzymes require specific pH ranges for proper folding and catalytic activity.

Flashcard 72: What happens to buffer capacity with equal concentrations of acid and base?

Answer: Buffer capacity is maximized. Equal concentrations create optimal conditions for resisting pH changes.

Flashcard 73: Identify a common laboratory buffer system.

Answer: The phosphate buffer system. $\text{HPO}_4^{2-} / \text{H}_2\text{PO}_4^-$ system with $\text{p}K_a$ of 7.2.

Flashcard 74: Calculate pH change: 0.01 mol NaOH in buffer capacity of 0.5.

Answer: ΔpH = 0.01/0.5 = 0.02. Using the buffer capacity equation to find resulting pH change.

Flashcard 75: What does Δn represent in the buffer capacity formula?

Answer: Δn is the amount of acid or base added. Moles of strong acid or base added to the buffer solution.

Flashcard 76: How does buffer capacity change with pH deviation from pKa?

Answer: It decreases as pH moves away from pKa. Maximum effectiveness occurs at pH = $\text{p}K_a$, declining as pH deviates.