Thymolphthalein – 5g

Thymolphthalein is a widely used laboratory indicator dye supplied in a convenient 5g pack, ideal for educational and teaching laboratories. Known for its clear and dramatic colour change, thymolphthalein is particularly valued in chemistry lessons where accurate visual results help reinforce key learning outcomes.

This compound has a CAS Number of 125‑20‑2 and no UN number assigned (UN: NR). It is typically supplied as a fine, pale solid and is commonly dissolved in alcohol to prepare indicator solutions. When used correctly, it provides a sharp colour transition in alkaline conditions, making it an excellent teaching aid for acid–base chemistry.

Clearly labelled and easy to store, thymolphthalein is suitable for routine use in school laboratories when handled in accordance with standard laboratory safety procedures.

Key Features

• Thymolphthalein indicator for laboratory use
• CAS No: 125‑20‑2
• UN No: NR
• Pack size: 5g
• Clear colour change in alkaline solutions
• Ideal for preparing indicator solutions
• Clearly labelled for safe identification and storage

Ideal for School Science Lessons

Thymolphthalein is particularly well suited to GCSE and A Level chemistry lessons, where it supports practical investigations into acids, bases, and pH ranges. Its distinct colour change makes it highly effective for helping students visually interpret chemical behaviour.

• Demonstrating acid–base indicators and pH ranges
• Supporting titration experiments under supervision
• Comparing indicator behaviour in weak and strong alkalis
• Developing practical skills in solution preparation
• Encouraging accurate observation and recording of results

Engaging, reliable, and visually clear, Thymolphthalein is an excellent addition to the school science laboratory, helping students build confidence in practical chemistry while deepening their understanding of core curriculum concepts.