To distinguish between the acid and base in the beaker, use a chemical indicator like phenolphthalein or natural indicators like turmeric, china rose, etc.
- In acid-base titrations, phenolphthalein is commonly used as an indicator; it turns colourless in acidic solutions and pink in basic solutions.
- Turmeric is of yellow colour. When turmeric paper is immersed in a basic solution, it turns red. Acid has no effect on the colour of turmeric paper.
- Another natural indicator is China rose. With acid, China rose solution turns dark pink and with base, it turns green.