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Phenolphthalein's pH sensitivity is exploited in other applications: concrete has naturally high pH due to the calcium hydroxide formed when Portland cement reacts with water. As the concrete reacts with carbon dioxide in the atmosphere, pH decreases to 8.5–9. When a 1% phenolphthalein solution is applied to normal concrete, it turns bright pink.
A drop of phenolphthalein reagent is added to the sample, and after a few seconds, a drop of hydrogen peroxide is applied to the swab. If the swab turns pink rapidly, it is said to test presumptive positive for blood. Waiting for periods over 30 seconds will result in most swabs turning pink naturally as they oxidize on their own in the air.
For optimal accuracy, the color difference between the two species should be as clear as possible, and the narrower the pH range of the color change the better. In some indicators, such as phenolphthalein, one of the species is colorless, whereas in other indicators, such as methyl red, both species confer a color. While pH indicators work ...
Solution: The main components of a universal indicator, in the form of a solution, are thymol blue, methyl red, bromothymol blue, and phenolphthalein. This mixture is important because each component loses or gains protons depending upon the acidity or alkalinity of the solution being tested. It is beneficial to use this type of universal ...
Other examples are phenolphthalein and thymolphthalein, colorless in acidic to neutral pH, but becoming pink and blue in alkaline environment. Other example are many redox indicators , which undergo reversible color change between colored and colorless form at a specific electrode potential .
Aircraft battling fires raging through the Los Angeles area are dropping more than water: Hundreds of thousands of gallons of hot-pink fire suppressant ahead of the flames in a desperate effort to ...
Three different points in an acid-base titration using phenolphthalein as the indicator. Phenolphthalein is widely recognized as one of the most commonly used acid-base indicators in chemistry. [12] Its popularity is because of its effectiveness in a broad pH range and its distinct colour transitions. [12]
In fact, as History Facts noted, sometimes, if oranges don't turn orange, they will be treated to turn into the orange hue we all know and love. Hopefully, next time you enjoy an orange, you'll ...