AP Chemistrymediummcq1 pt
Which mixture produces a buffer with pH closest to 9.0?
A.NH₄⁺/NH₃ (pKa = 9.25)
B.CH₃COOH/CH₃COO⁻ (pKa = 4.74)
C.HF/F⁻ (pKa = 3.20)
D.H₂CO₃/HCO₃⁻ (pKa = 6.35)
Explanation
Core Concept
Buffers hold pH near their pKa, and ammonium/ammonia's 9.25 is the closest match to 9.0.
Correct Answer
ANH₄⁺/NH₃ (pKa = 9.25)
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