alleryStart learning →A buffer is needed to hold a solution at pH 9.5. Which pair should be chosen?
AA weak acid together with its own salt
BA strong acid together with its own salt
CA strong base together with its own salt
DA weak base together with its own salt
Answer & Solution
Correct answer: D. A weak base together with its own salt
1. A buffer works best near the pH set by its own conjugate pair.
2. Weak acids and their salts hold that point below 7 on the scale.
3. Weak bases and their salts hold it above 7 instead.
4. A target of 9.5 lies above 7, so a weak base with its salt is the right choice.
5. Strong acids and strong bases have no weak conjugate partner, so they cannot buffer.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 14 "Acid-Base Equilibria", section 14.6 Buffers_
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