AP Chemistrymediummcq1 pt
A 1.0 L buffer contains 0.10 mol HA and 0.10 mol A⁻. After 0.010 mol of strong acid is consumed by the buffer, what is the new [A⁻]/[HA] ratio?
A.0.82
B.1.0, unchanged
C.1.22
D.0.10
Explanation
Core Concept
Added strong acid converts A⁻ into HA one mole for one mole. The buffer ends holding 0.090 mol A⁻ and 0.110 mol HA, so the ratio becomes 0.090 ÷ 0.110 ≈ 0.82. The small drift shows the buffer absorbing the added acid while the pH eases slightly below pKa.
Correct Answer
A0.82
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