Phenolphthalein
Reagent-grade Phenolphthalein (CAS 77-09-8) powder and solutions supplied by Zyntex for laboratory and industrial use. Acid–base indicator for titrations, alkalinity test kits and concrete carbonation testing. CoA and SDS.
Description
Phenolphthalein Product Overview
Phenolphthalein (C20H14O4) is a white to slightly yellow crystalline powder that is insoluble in water and dissolves in ethanol. It is colorless in acidic and neutral solutions and turns pink to magenta above about pH 8.2–10.
In addition, laboratories use it as the classic indicator in acid–base titrations, and test kit producers use it in water alkalinity tests. Similarly, construction engineers spray phenolphthalein solution on concrete to measure the depth of carbonation. It was formerly used as a laxative, but this use was withdrawn in the US and other markets, and the EU classifies it as a carcinogen (category 1B), so Zyntex supplies it only for laboratory and industrial uses.
Notably, related laboratory chemicals in our range include EGTA and Silver Nitrate.
Key Applications of Phenolphthalein
Typical uses include, for example:
🔬 Titrations
Acid–base indicator.
🧪 Test Kits
Water alkalinity.
🏗️ Concrete Testing
Carbonation depth.
📚 Education
Teaching laboratories.
Phenolphthalein Technical Specifications
| Parameter | Standard Value |
|---|---|
| Product Name | Phenolphthalein |
| CAS Number | 77-09-8 |
| Molecular Formula / Weight | C20H14O4 / 318.32 g/mol |
| Transition Range | pH 8.2 (colorless) – 10.0 (pink) |
| Grade | Reagent (ACS) |
| Regulatory Note | EU carcinogen category 1B; laboratory and industrial use only |
| Documents | CoA and SDS with every lot |
⚠️ Safety & Handling: May cause cancer, is suspected of causing genetic defects and may damage fertility. Avoid dust and contact, and also wear gloves, eye protection and dust protection. Store locked in tightly closed containers. Always consult the Safety Data Sheet (SDS), because it contains the full classification and handling instructions.
Frequently Asked Questions
At what pH does phenolphthalein change color?
It turns from colorless to pink between about pH 8.2 and 10.
Is it used as a laxative?
No longer; that use was withdrawn, and Zyntex supplies it only for laboratory and industrial use.
How can I get a price and documents?
We supply flexible quantities, from small orders to large volumes, so you do not need to meet the high minimum orders of large producers. Please contact us with your required volume, and we will send a quotation together with the CoA and SDS.
