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Chemistry / Practical
Watch a pH curve happen one drop at a time.
Run a strong acid against a strong base. Move the burette, follow the indicator and stop at the equivalence point.
40 min Advanced 2D / browser
Live demo / no sign in requiredBuilt with demo data
Virtual bench / acid base
SimulatedStrong acid into strong base.
pH
3.09
Strongly acidic
Base added
24.6 mL
n(OH-)
2.46 mmol
Phenolphthalein stays colourless below pH 8.2. Keep adding base slowly.
Live readout
Acid in excess24.6
mL NaOH addedBurette control24.6 / 50.0 mL
pH against volume
Equivalence at 25 mLAcid is still in excess. Almost every drop of base is neutralised, so the pH is set by the hydrogen ions that remain.
Before equivalence
0 to 24.9 mL
Excess HCl sets the pH. Adding base changes it slowly at first.
At equivalence
25.0 mL
Moles of acid equal moles of base. The solution is neutral.
After equivalence
25.1 to 50 mL
Excess NaOH sets the pH. The curve flattens as OH- is diluted.
What this demo shows
- Add base in 0.1 mL steps and watch the pH respond.
- The curve marks the equivalence point at exactly 25.0 mL.
- Switch the indicator off to read the chemistry without the colour.
Keep the model. Keep the progress.
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