This morning, Manager Wang of our company received a message from the technical staff, mainly about sodium hydroxide. The CAS number of this product is 1310-73-2, which is also a popular product. Our company's technical staff proposed to release the sodium hydroxide deterioration detection method, because many friends have already asked this question. Below, Hengyuan answers: How to detect whether sodium hydroxide has deteriorated?
The detection method requires four steps. Let ’s look at the first step first: if excessive diluted hydrochloric acid is added dropwise to the sample, if bubbles are generated, sodium hydroxide will deteriorate.
Principle: 2NaOH + CO? ==== Na? CO? + H? O
2HCl + Na? CO? ==== 2NaCl + CO? ↑ + H? O
(The air contains a small amount of carbon dioxide, and the open NaOH solution can react with CO?
(Hydrogen ions in HCl can react with carbonate ions to generate gas)
Note: HCl will preferentially react with NaOH to form NaCl and H? O. Because NaOH is a strong base, and Na? CO? Is alkaline in aqueous solution.
In the second step, clarified lime water is added to the sample. If a white precipitate is formed, the sodium hydroxide deteriorates.
Principle: Na? CO? + Ca (OH)? ==== CaCO? ↓ + 2NaOH
In the third step, barium chloride is added to the sample. If a white precipitate is formed, the sodium hydroxide deteriorates.
Principle: Na? CO? + BaCl? ==== BaCO? ↓ + 2NaCl
The fourth step, partial deterioration: â‘ Adding BaCl? Or BaNO ?, there is precipitation, which proves to be Na? CO ?, after the precipitation is completely still, take the supernatant in the test tube, dropwise add colorless phenolphthalein solution, phenolphthalein changes Red, proved to have NaOH.
Note: If NH? Cl is not added dropwise, Na? CO? Will become alkaline after dissolving in water because there will be OHˉ root ions, and NH? + And OHˉ will also have a pungent smell when combined with it, so it cannot.
â‘¡ Add calcium chloride to NaOH, if there is white precipitation, it means that NaOH has deteriorated. Add colorless phenolphthalein, if colorless phenolphthalein does not change color, it means completely deteriorated. If the colorless phenolphthalein turns red, it means that part of it has deteriorated
Have you been looking for this article for a long time? The above four specific steps for the detection of sodium hydroxide are here. Shanghai Hengyuan Biochemical Reagent Co., Ltd. needs "sodium hydroxide". You are welcome to call to order. Preferential activities, and give small gifts such as U disk and mouse!
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