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Mistake Master · AP Chemistry · Unit 8 · Step-Through Animation

Same Acid, Two Flasks, Opposite Answers

You'll learnhow comparing a solution's pH with the acid's own pKa tells you which form, HA or A⁻, is sitting in the flask.

One weak acid goes into two solutions. In one flask it comes out almost entirely intact; in the other, almost entirely stripped of its proton. Nothing about the molecule changed. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · pH < pKa → HA · pH > pKa → A⁻ · v2

one acid · two solutions · the comparison that decides it
Before you start
What you're looking at
The same weak acid in two solutions, drawn as bars showing how much of it is intact and how much has lost its proton.
The question
Nothing about the molecule changed, so what decides which form you find?
Step 1 / 12