Titration Drip

Students drag the tap handle on a burette to run 0.100 mol/L NaOH into 25.0 mL of acid, or click the handle for one 0.05 mL drop at a time. The flask changes colour according to the chosen indicator while the pH readout and curve climb, jumping steeply near equivalence. They can switch between strong and weak acid and three indicators. It shows why drop-by-drop control matters near the endpoint and how n = c x V finds an unknown concentration. Teachers can compare indicators or hydrochloric against ethanoic acid.

• Drag the tap handle down to run base into the flask and watch Base added and pH of flask.
• Click the handle for single drops as the colour starts to change near the endpoint.
• Compare Phenolphthalein, Bromothymol blue and Methyl orange on the same acid.
• Switch the acid to Ethanoic acid 0.100 M and compare its starting pH and curve with hydrochloric acid.
• Note the Equivalence at readout, then press Refill and restart and try to stop exactly on it.

1. 1Describe how a titration finds the amount of acid using a base of known concentration.
2. 2Identify the equivalence point from the steep rise on a pH curve.
3. 3Compare strong and weak acid titration curves.
4. 4Explain how an indicator is chosen to match the pH at the endpoint.

Questions teachers ask