pH and indicators

Aim

Use indicator colours to compare dilute solutions and estimate their pH.

1. Use an indicator to recognise acidic, neutral, and basic solutions.
2. Explain the uncertainty in a colour-chart pH estimate.
3. Connect a one-unit pH difference to a tenfold change in hydronium-ion concentration.

Apparatus

1. Labelled beakers of teacher-prepared dilute solutions
2. Universal indicator paper with its own colour chart
3. Clean droppers, white tile, and protective eyewear