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Buffers

Chemistry • Acid–Base Equilibria • Knowledge-Based • 5 questions

Buffers Knowledge-Based Download PDF

Chemistry · Acids & Bases · Chemistry · Acid–Base Equilibria

5 Chemistry practice questions on Buffers. Questions that assess core concepts and understanding.

Questions

  1. 1.

    A buffer solution is prepared containing a weak acid (HA) and its conjugate base (A−\text{A}^-). If the molar concentration ratio of conjugate base to weak acid, [A−]/[HA][\text{A}^-]/[\text{HA}], is equal to 10, how does the resulting pH of the buffer compare to the pKa\text{p}K_a of the weak acid?

    • A) The pH is equal to pKa−1.0\text{p}K_a - 1.0.
    • B) The pH is equal to pKa+1.0\text{p}K_a + 1.0.
    • C) The pH is equal to pKa\text{p}K_a.
    • D) The pH is equal to 10×pKa10 \times \text{p}K_a.
  2. 2.

    Under which of the following conditions does a weak acid and conjugate base buffer solution exhibit its maximum buffer capacity at a given total concentration?

    • A) When the concentration of the weak acid is significantly greater than that of its conjugate base
    • B) When the pH of the solution is at least two units greater than the pKapK_a of the weak acid
    • C) When the molar concentrations of the weak acid and its conjugate base are equal
    • D) When the acid dissociation constant KaK_a of the weak acid equals 1.0×10−141.0 \times 10^{-14}
  3. 3.

    How does diluting an aqueous buffer solution containing equimolar amounts of a weak acid and its conjugate base with pure water affect its pH and its buffer capacity?

    • A) Both the pH and the buffer capacity increase significantly.
    • B) The pH changes substantially, while the buffer capacity remains unchanged.
    • C) The pH decreases significantly, while the buffer capacity increases.
    • D) The pH remains essentially unchanged, while the buffer capacity decreases.
  4. 4.

    When a small amount of a strong acid is added to an acetic acid/sodium acetate buffer solution, which chemical species primarily reacts to neutralize the added hydronium ions?

    • A) Acetic acid molecules, CH3COOH\text{CH}_3\text{COOH}
    • B) Water molecules, H2O\text{H}_2\text{O}
    • C) Acetate ions, CH3COO−\text{CH}_3\text{COO}^-
    • D) Sodium ions, Na+\text{Na}^+
  5. 5.

    Which of the following aqueous mixtures forms an effective buffer solution when mixed in equal volumes?

    • A) 0.10 M HCl and 0.10 M NaCl
    • B) 0.10 M CH3COOH and 0.10 M CH3COONa
    • C) 0.10 M NaOH and 0.10 M NaCl
    • D) 0.10 M HNO3 and 0.10 M HCOOH