Question

Select the statement that best describes a buffer. View Available Hint(s) Select the statement that best describes a buffer. A buffer prevents the pH of a solution from changing when an acid or base is added. Buffered solutions are always neutral, with a pH of 7. A buffer stabilizes the pH of a solution by preventing acids or bases from dissociating. A buffer causes acidic solutions to become alkaline, and alkaline solutions to become acidic. A buffer resists change in pH by accepting hydrogen ions when acids are added to the solution and donating hydrogen ions when bases are added.

Answer 1

The statement that best describes a buffer is: A buffer resists change in pH by accepting hydrogen ions when acids are added to the solution and donating hydrogen ions when bases are added.

Why?

A buffer is a solution made by combining either:

1. A weak acid (HA) and its conjugate base (A⁻).
2. A weak base (B) and its conjugate acid (HB⁺)

The purpose of a buffer is to resist changes in pH when a strong acid or base is added to the solution.

If the buffer is composed of HA and A⁻ and a strong acid (e.g. HCl) is added, the buffer accepts hydrogen ions in the following way:

A⁻+HCl → HA+Cl⁻

If a strong base (e.g. NaOH) is added, the buffer donates hydrogen ions in the following way:

HA + NaOH → NaA + H₂O

The pH of the buffer at any given moment can be found by using the Henderson-Hasselbach equation, based on the equilibrium HA + H₂O ⇄ H₃O⁺ + A⁻

$pH=pKa+log\frac{[A^{-}] }{[HA]}$

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Answer 2

Answer:

A buffer resists change in pH by accepting hydrogen ions when acids are added to the solution and donating hydrogen ions when bases are added.

Explanation:

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