Learn the procedure for making a dithizone indicator solution.
The compound that changes color when exposed to acidic or basic solutions is called an indicator. Most of the time, color indicators are used to measure pH. To find the endpoint or equivalence point of the titration, they are added to the reaction mixture.
Dithizone (C13H12N4S) is a sulfur-containing organic compound chemically described as 1,5-diphenylthiocarbazone, which is used as a complexometry/metal indicator. It comes in the form of crystalline black powder which is soluble in ethanol but insoluble in water.
It is a good ligand and can form complexes with several toxic metals, including lead, thallium, and mercury. Additionally, it acts as a chelating agent for toxic metals including lead and mercury.
How to prepare dithizone indicator for titration:
- Accurately weigh 25 mg of dithizone and pour it into a 100 mL volumetric flask with 50 ml of ethanol.
- Once it is dissolved, dilute it to 100.00 mL with ethanol.
- The concentration of the prepared solution is about 01 g/L.
Dithizone has a pKa of 1:4.50;pK2:15 (25°C), When used as an indicator, it produces a pink color in a pH range of 4 to 5 when zinc ions are present, and a green color when these ions are absent.
References:
Wikipedia contributors. (2022, August 9). Dithizone. In Wikipedia, The Free Encyclopedia. Available Here:
Law.resource.org. 2022. [online] Available Here:
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