Phenol red solutions are widely used pH indicators that change color with acidity, turning yellow in acidic conditions (below pH 6.8), red/pink in neutral/basic conditions (above pH 8.2), and are crucial for monitoring cell culture health, testing water quality (pools, spas, drinking water), and demonstrating acid-base chemistry like CO2 presence in breath. They offer a simple visual method for quick pH assessment, turning orange/yellow as acidity increases and pink/red as alkalinity increases.
How it works
- Acidic (pH < 6.8): Turns yellow.
- Neutral/Slightly Basic (pH ~7.0 – 8.0): Red/Orange.
- Basic (pH > 8.2): Pink/Fuchsia.
Common Uses
- Cell Culture Media: Detects metabolic waste (lactic acid) by turning media yellow, signaling acidification.
- Water Testing: For pools, spas, aquariums, and drinking water to check pH levels (often in the 6.5-8.5 range).
- Biology Experiments: Shows how exhaled breath (containing CO2, which forms carbonic acid) changes solution pH.
- Lab Indicator: Used in various assays and titrations.
Key Characteristics
- Colorimetric: Provides a clear visual pH reading.
- Applications: Works in water-based systems, but salt water can interfere.
- Safety: Can be an irritant; handle with gloves and eye protection.