Acids and alkalis are colourless so you need an indicator to tell the difference.
Single indicators change colour at the end point eg litmus or phenylthalein
Mixed indicators change colour at lots of different points eg. universal indicators (which tell you the PH)
Adding acid to alkali:
Adding alkali to acid:
The concentration of an acid or alkali can be calculated by carrying out an experiment called titration.
- Pipette filler
- Conical flask