All flashcards
Flashcard 1: Identify a common laboratory buffer system.
Answer: The phosphate buffer system. HPO42−/H2PO4− system with pKa of 7.2.
Flashcard 2: How does dilution affect buffer capacity?
Answer: Dilution decreases buffer capacity. Lower concentrations mean fewer buffer molecules to resist pH changes.
Flashcard 3: 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 4: 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 = pKa and ratio is 1:1.
Flashcard 5: 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 6: 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 7: 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: ΔpH=Δn÷capacity.
Flashcard 8: 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 9: Identify the formula for calculating buffer capacity.
Answer: Buffer capacity = Δn/ΔpH. Where Δn is moles added and ΔpH is the resulting pH change.
Flashcard 10: Which factors affect buffer capacity?
Answer: Concentration of buffer components and their ratio. Higher concentrations and equal ratios provide maximum buffering effectiveness.
Flashcard 11: 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 12: 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 13: 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 14: Identify the primary buffer system in human blood.
Answer: The bicarbonate buffer system. HCO3−/H2CO3 system maintains blood pH around 7.4.
Flashcard 15: 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 16: What determines the effective pH range of a buffer?
Answer: The pKa of the acid and the concentration ratio. Buffer works best within pKa±1 pH unit range.
Flashcard 17: 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 18: 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 19: What is the relationship between buffer capacity and buffer range?
Answer: Buffer capacity is highest within the buffer range. Buffer range (pKa±1) defines where capacity is most effective.
Flashcard 20: 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 pKa for maximum effectiveness.
Flashcard 21: 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 22: How does buffer capacity change with pH deviation from pKa?
Answer: It decreases as pH moves away from pKa. Maximum effectiveness occurs at pH = pKa, declining as pH deviates.
Flashcard 23: How does dilution affect buffer capacity?
Answer: Dilution decreases buffer capacity. Lower concentrations mean fewer buffer molecules to resist pH changes.
Flashcard 24: 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 25: Identify a common laboratory buffer system.
Answer: The phosphate buffer system. HPO42−/H2PO4− system with pKa of 7.2.
Flashcard 26: 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 27: 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: Δn/ΔpH.
Flashcard 28: 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 pKa±1 pH unit.
Flashcard 29: 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 30: How does temperature affect buffer capacity?
Answer: Temperature can affect dissociation and thus buffer capacity. Higher temperatures increase ionization, affecting buffer equilibrium.