Learn the procedure for making a crystal violet indicator solution.
The compound that changes color when exposed to acidic or basic solutions is called an indicator. Color indicators are commonly used to measure pH and are added to the reaction mixture to identify the titration endpoint/equivalence point.
Crystal violet (C25H30ClN3) also known as methyl violet, gentian violet, or hexamethyl pararosaniline chloride is a triarylmethane dye used as a histological stain and indicator. It comes in powder form and appears as a dark green compound with a metallic luster however appears purple when dissolved.
Methyl violet is soluble in water, alcohol, chloroform, and insoluble in ether. It can be used to make paints and inks for printing. It can also be used as an acid-base indicator, as well as a colorimetric assay development reagent.
How to prepare crystal violet indicator for titration:
- Weigh accurately 0.5 gm of crystal violet and pour it into a 100.00 ml volumetric flask containing 50.00 ml of acetic acid and swirl until it completely dissolved.
- Once it is dissolved, dilute to 100.00 ml with acetic acid.
- The concentration of the prepared solution is about 05.00 gram/liter.
Crystal violet has pKa values of 9.4. Its pH range is 0.0 to 2.0. In an acidic medium, Crystal violet gives yellowish-green, while in a basic condition, it turns violet color. It is the most commonly used indicator in non-aqueous titrations, as well as also used for acid-base titration.
References:
- Wikipedia contributors. (2022, February 13). Crystal violet. In Wikipedia, The Free Encyclopedia. Available Here:
- Law.resource.org. 2022. [online] Available Here:
- Preparation of Indicator Solutions : Pharmaceutical Guidelines. Available Here:
- ‘Recipe for Crystal Violet for the Gram Stain’. ThoughtCo, Available Here:
You may also like this:
No comments:
Post a Comment