Worksheet: Buffer Capacity

In this worksheet, we will practice calculating the maximum amount of acid/base a buffer can neutralize before pH is significantly affected.

Q1:

What mass of solid NaCHCO·3HO322 in grams must be added to 0.300 L of a 0.50 M acetic acid solution to produce a buffer with a pH of 5.00? Assume a negligible change in volume as the solid is added. The 𝐾a of acetic acid is 1.8×10.

Q2:

Which of the following, if added to a buffer of acetic acid and sodium acetate, would decrease the concentration of CHCOH32?

  • AKOH
  • BHCl
  • CCHCOH32
  • DKCHCO32
  • ENaCl

Q3:

Which of the following, if added to a buffer of acetic acid and sodium acetate, would decrease the concentration of CHCO32?

  • ACHCOH32
  • BNaCl
  • CHCl
  • DKOH
  • EKCHCO32

Q4:

Which of the following, if added to a buffer of ammonia and ammonium nitrate, would decrease the concentration of NH3?

  • AKI
  • BNaOH
  • CNH3
  • DNHCl4
  • EHI

Q5:

Which of the following, if added to a buffer of ammonia and ammonium nitrate, would decrease the concentration of NH4+?

  • AKI
  • BNH3
  • CNHCl4
  • DNaOH
  • EHI

Q6:

Why does the pH not change significantly when a small amount of an acid or a base is added to a solution that contains equal amounts of the acid HPO34 and NaHPO24, a salt of its conjugate base?

  • ANaHPO24 reacts with excess base, while HPO34 reacts with excess acid.
  • BExcess base is removed by reaction with HPO34, while excess acid is removed by reaction with NaHPO24.
  • CHPO34 is amphiprotic and reacts with and neutralizes both acids and bases; NaHPO24 then converts to HPO34, restoring the pH.

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