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Buffer quiz #2

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Terms in this set (39)

  • Which of the buffer systems is not capable of raising and lowering the pH?
    A buffer system with only a strong acid or strong base is not capable of raising and lowering the pH effectively.
  • A 1.0 L buffer solution is 0.15 M in HCN and 0.10 M in NaCN. Which action will destroy the buffer?
    Adding too much strong acid or strong base will destroy the buffer.
  • Which combination cannot function as a buffer solution?
    A combination of a strong acid and its salt cannot function as a buffer solution.
  • What ratio of CH3NH2 to CH3NH3+ is needed to prepare a pH 9.90 buffer? (Kb for CH3NH2 is 4.4 × 10⁻⁴)
    Use the Henderson-Hasselbalch equation: pH = pKa + log([base]/[acid]). Calculate pKa from Kb, then solve for the ratio.
  • What is a false statement about buffers?
    A false statement would be: Buffers are made from strong acids and strong bases.
  • What ratio of CH3NH2 to CH3NH3+ is needed to prepare a pH 9.70 buffer? (Kb for CH3NH2 is 4.4 × 10⁻⁴)
    Use the Henderson-Hasselbalch equation: pH = pKa + log([base]/[acid]). Calculate pKa from Kb, then solve for the ratio.
  • How many milliliters of each solution would you use to make approximately a liter of the buffer?
    Use equal volumes of the weak acid and its conjugate base (or weak base and its conjugate acid) to make a buffer, adjusting concentrations as needed for 1 L.
  • What combinations make a good buffer?
    A weak acid and its conjugate base, or a weak base and its conjugate acid, in similar concentrations make a good buffer.
  • What type of mixture will act as a buffer when dissolved in water?
    A mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid, will be a buffer.
  • Which conjugate pair is suited best to make this buffer?
    The best conjugate pair is one where the pKa is close to the desired pH of the buffer.
  • Evaluate the buffer. What is its capacity to resist pH change?
    The buffer's capacity depends on the concentrations of the weak acid and conjugate base; higher concentrations provide greater capacity.
  • Which is a possible example of species that can comprise a buffer solution?
    Acetic acid (CH3COOH) and sodium acetate (CH3COONa) are an example of a buffer pair.
  • What best describes a buffer?
    A buffer is a solution that resists changes in pH when small amounts of acid or base are added.
  • What is the function of a buffer in a solution?
    A buffer is a solution that minimizes changes in pH upon addition of small amounts of acid or base.
  • Buffers are substances that help resist shifts in pH by
    Buffers resist shifts in pH by neutralizing added acids or bases.
  • What does a buffer generally do?
    A buffer maintains a relatively constant pH by neutralizing added acids or bases.
  • An acid-base buffer system stabilizes pH by ______ or ______, as needed.
    An acid-base buffer system stabilizes pH by neutralizing added H+ or OH- ions, as needed.
  • Which substance in a buffer donates H+ ions?
    The weak acid in a buffer donates H+ ions to neutralize added base.
  • The primary role of the carbonic-acid-bicarbonate buffer system is to
    The carbonic-acid-bicarbonate buffer system helps maintain blood pH by neutralizing acids and bases.
  • What is true about pH buffers?
    pH buffers resist changes in pH when small amounts of acid or base are added.
  • What is true about the effectiveness of buffer solutions?
    Buffer solutions are most effective when the concentrations of weak acid and conjugate base are similar.
  • Of the following solutions, which has the greatest buffering capacity?
    The solution with the highest concentrations of both weak acid and conjugate base has the greatest buffering capacity.
  • Buffers work best when ...
    Buffers work best when the concentrations of weak acid and conjugate base are equal or nearly equal.
  • A buffer is a substance that
    A buffer is a substance that resists changes in pH when small amounts of acid or base are added.
  • Describe the purpose of a buffer.
    The purpose of a buffer is to maintain a stable pH in a solution.
  • Determine whether or not each combination of substances can be used to create a buffer.
    A combination can create a buffer if it contains a weak acid and its conjugate base, or a weak base and its conjugate acid.
  • Which pair of compounds will form a buffer in aqueous solution?
    A weak acid and its conjugate base, or a weak base and its conjugate acid, will form a buffer in aqueous solution.
  • How do buffers resist changes in pH?
    Buffers resist changes in pH by neutralizing added acids or bases through reactions with their weak acid or conjugate base components.
  • Why do we need to add buffer into the master mix?
    A buffer is added to the master mix to maintain a stable pH during chemical or biological reactions.
  • What defines a buffer solution?
    A solution containing a weak acid and its conjugate base, or a weak base and its conjugate acid, is a buffer solution.
  • What is the primary function of a buffer in a solution?
    The primary function of a buffer is to resist drastic changes in pH when small amounts of strong acid or base are added.
  • How is a chemical buffer generally described?
    A chemical buffer is generally described as a solution containing a weak acid and its conjugate base, or a weak base and its conjugate acid, which resists changes in pH.
  • What is the most significant role played by pH buffers in chemical or biological systems?
    The most significant role of pH buffers is to maintain a stable pH by neutralizing added acids or bases.
  • What effect does a buffer have on a solution when acid or base is added?
    A buffer minimizes the change in pH of a solution when small amounts of acid or base are added.
  • What is the primary role of the carbonic-acid-bicarbonate buffer system in the body?
    The primary role of the carbonic-acid-bicarbonate buffer system is to help maintain the pH of blood and other bodily fluids within a narrow range.
  • Why are buffers useful to cells?
    Buffers are useful to cells because they help maintain a stable internal pH, which is essential for proper cellular function and enzyme activity.
  • What is a buffer solution?
    A buffer solution is a solution that contains a weak acid and its conjugate base, or a weak base and its conjugate acid, and resists changes in pH upon addition of small amounts of acid or base.
  • Which substance commonly acts as a buffer in natural water systems?
    Bicarbonate ions commonly act as a buffer in natural water systems.
  • What combination of substances could create a buffer solution?
    A buffer solution can be created by combining a weak acid with its conjugate base, or a weak base with its conjugate acid.