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Buffer Capacity

Buffer capacity is how much added acid or base a buffer can absorb before its pH changes significantly. A more concentrated buffer has a larger reservoir of both components, so it holds its pH longer. Two buffers at the same pH can differ greatly in capacity if their concentrations differ.

UNIT 8 TOPIC 8.10 • BUFFER CAPACITY BUFFER CAPACITY Buffer capacity = how much strong acid or base a buffer absorbs before pH changes sharply. MORE CONCENTRATION → HOLDS pH LONGER both start at pH = pKa strong acid / base added → pH change LOW conc. small capacity HIGH conc. large capacity SAME pKa — DIFFERENT CAPACITY LOW TOTAL 0.10 M HA 0.10 M A⁻ HIGH TOTAL 1.0 M HA 1.0 M A⁻ Equal [HA] = [A⁻] ratio → both start at the same pH (pH = pKa), but capacity differs. WHY THE CONCENTRATED ONE WINS Higher total concentration provides more HA and A⁻ particles to neutralize the added strong acid or base. So it holds its pH far longer before the sharp rise — greater buffer capacity. CED ANCHOR The ratio [A⁻]/[HA] sets the pH; the absolute amounts of the conjugate pair set the buffer capacity. AP Chemistry · Unit 8 · Acids and Bases
Buffer capacity is how much acid or base a buffer can absorb before its pH changes significantly. A more concentrated buffer has a larger reservoir, so it holds its pH longer. Capacity is finite: enough added acid or base eventually overwhelms it.
Capacity Stress · Open the sandbox →

The trap misconceives buffer capacity — treating it as unlimited, or as set by the pH rather than the amount of buffer. Capacity is finite and grows with concentration; enough added acid or base will eventually exhaust it.

The work

3 ways in · any order
Lesson
Buffer Capacity ›

Buffer capacity grows with concentration and is finite: enough added acid or base overwhelms it. The lesson relates capacity to concentration, then closes with a ten-scenario check.

Skill check · 10 scenarios
Open lesson →
Diagnostic
10-item topic check ›

Ten items spanning the Topic 8.10 misconception: buffer capacity misconceived — treated as unlimited or as set by pH rather than concentration.

Not started · 10 items · ~15 min
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Targeted Practice
Drill a single misconception ›

Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.

Take the diagnostic to identify your misconceptions
Diagnostic first