Which of the following yields a buffer solution when equal volumes of the two solutions are mixed A) 0.10M H₂CO₃ and 0.050M HCl B) 0.10M H₂CO₃ and 0.10M KOH C) 0.10M H₂CO₃ and 0.10M HCl D) 0.10M H₂CO₃ and 0.050M KOH E) 0.10M K₂CO₃ and 0.050M KOH

Question

Quizplus · Accepted Answer

A buffer solution requires a weak acid and its corresponding conjugate base (or a weak base and its corresponding conjugate acid) to resist changes in pH when small amounts of acid or base are added. 
Choice A only has a weak acid and a strong acid, and Choice C only has a weak acid and a strong base, so they cannot form a buffer. Choice B has a weak acid and a strong base, which will react completely to form water and a salt, so it also cannot form a buffer. 
Choice D has a weak acid (HSO4-) and its conjugate base (SO42-) at equal concentrations, which can act as a buffer. Choice E has a strong base and its corresponding conjugate acid, which will react completely to form water and a salt, so it also cannot form a buffer.

Which of the Following Yields a Buffer Solution When Equal