Indicators

Molecules that change colour

An interactive lesson with 4 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Indicators are weak acids with different-coloured acid and base forms.
• They change over about pKa ± 1.
• Choose one whose range sits on the steep jump of the titration.

Steps

1. An acid that changes colour
2. Choose the indicator
3. Red cabbage
4. Strong acid, strong base