We supply phenolphthalein in 500ml containers, with discounts available on bulk orders. This is our most popular phenolphthalein product, but we also offer a 0.05 w/v solution. We also offer more options with all our products, from customised labelling to specific pack sizes. Simply contact us for further information or free technical advice.
Phenolphthalein is a Popular pH Indicator
With the formula C20H14O4, phenolphthalein is a common pH indicator, turning colourless in acidic solutions or pink in alkaline solutions. As such, it’s very popular to titrate acid-base reactions. This compound is insoluble in water and is typically prepared in alcohol solutions.
It works because the molecule version is colourless, but the ionic version is pink. When a base is added to the solution, the balance between molecule and ions is altered towards the ionic side, resulting in more H ions being removed from the molecule (with the subsequent production of phenolphthalein ion, which is pink). As a result, for pH below 8.2, the solution is colourless, but changes to pink when pH reaches 10.
Other Uses of Phenolphthalein
Despite being a popular pH indicator, this compound can be used in other applications:
As a laxative, but its popularity is decreasing over fears of being carcinogenic after prolonged use
In the Kastle-Meyer test to identify the presence of blood. In this case, a sample suspected of containing blood is treated with alcohol and phenolphthalein, followed by a few drops of hydrogen peroxide. If the sample contains haemoglobin, it turns pink. This is commonly used as the first analysis for its easiness, with the added bonus of not destroying the sample, which can later be used for other tests.
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8.3 - 10 Colourless to Red
Hazard Statement Code
Causes serious eye irritation.
May cause cancer.
Suspected of causing genetic defects.
May cause damage to organs .
Highly flammable liquid and vapour.
Precautionary Statement Code
Do not breathe vapour/ spray.
Wear protective gloves/ protective clothing/ eye protection/ face protection.
IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Obtain special instructions before use.
Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
Do not eat, drink or smoke when using this product.
ReAgent has been a leading UK chemical supplier for over 40 years. With accreditation to a number of ISO Standards, as well as a 100% quality guarantee on every product, we have the knowledge and experience to handle all of your business needs.
You can buy phenolphthalein from our online chemical shop in 500ml containers. Order online today where you can also get nationwide next-day delivery and discounts on bulk orders.
We also have extra, industry-leading services available on all products, including personalised labelling, customisable packaging and the choice of specific pack sizes. Simply contact us for further information.
What is Phenolphthalein?
Phenolphthalein is one of the most widely used indicators. In its pure form, it appears as a white powder.
One of the most frequent uses of this product is for detecting the end-point in acid-base titrations. For this application, phenolphthalein is effective for many different acids, such as hydrochloric acid.
Phenolphthalein as an Indicator
To detect the strength of the hydrochloric acid, phenolphthalein indicator is first dissolved in a solvent like industrial methylated spirits (IMS) or denatured alcohol. It is then added to a vessel containing HCl.
Once the indicator has been added, the solution can be titrated using a base of a known concentration, like sodium hydroxide. When the solution turns pink, it shows the end-point of the titration and you can calculate the strength of the hydrochloric acid from the amount of sodium hydroxide required.
Phenolphthalein is used more often with stronger acids and bases. This is because it takes effect at a relatively high pH, usually between pH 8.3 and pH 10.
Phenolphthalin, a reduced and colourless form of phenolphthalein, is often used in the Kastle-Meyer test. This process is done to identify whether there is a presence of blood in a given substance.
A few drops of alcohol and phenolphthalin are added to a dry sample. Hydrogen peroxide is then dripped onto it as well. The sample will immediately turn pink if there is a presence of haemoglobin, showing that there is likely content of blood. This happens because of the hydrogen peroxide as well as the generation of phenolphthalein taking place.
Interestingly, phenolphthalein has been widely used as a laxative since its discovery. Please note, however, that all products manufactured and supplied by ReAgent are not suitable for human consumption unless clearly stated.
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Place your order online today, or contact our technical sales team for more information. We'll be happy to help you before, during and even after your purchase.