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Fun chemistry experiment—how luminol emits blue light

2019-04-03 来源:亚科官网
 
Luminol is one of the most commonly used chemiluminescent reagents. When oxidized by peroxide, it produces an excited state product, aminophthalate. This product decays to a low energy state while releasing photons. Patented additives can increase the luminescence intensity and duration (stability) of the luminol reaction, thereby enabling enhanced chemiluminescence (ECL).
The principle of luminol luminescence
First, sodium hypochlorite oxidizes luminol to cause it to emit light;
The second is that hydrogen peroxide reacts with sodium hypochlorite to form oxygen to oxidize luminol to cause it to emit light:
The first is the equation for the reaction of sodium hypochlorite and hydrogen peroxide: NaClO + H2O2 == NaCl + O2 + H2O
Secondly, luminol reacts with hydroxide to form a double anion (Dianion) which is oxidized by oxygen decomposed by hydrogen peroxide and the product is an organic peroxide. The peroxide is very unstable and immediately decomposes nitrogen (Luminol is oxidized by an organic oxidant such as dimethyl sulfoxide, which does not generate nitrogen, but forms a nitrogen-containing organic substance) to form an excited state of 3-aminophthalic acid. In the transition from the excited state to the ground state, the released energy exists in the form of photons, and the wavelength is in the blue portion of the visible light.
Luminol luminescence experiment
First, reagent materials: concentrated ammonia, luminol, 10% sodium hypochlorite solution (based on effective chlorine content), 30% hydrogen peroxide solution
Second, the experimental steps
1. A mixed solution of alkaline luminol and hydrogen peroxide is provided, and the alkaline condition is provided by ammonia water.
Measure 420 mL of water, weigh 0.05 g of luminol and add luminol to 420 mL of water, and it will be found that luminol is difficult to dissolve. 20 mL of concentrated ammonia water was weighed and mixed with 0.05 g of luminol and 420 mL of water, and it was observed that luminol was gradually dissolved in the alkaline solution. After the luminol is completely dissolved, 10-20 drops of a 30% hydrogen peroxide solution are added thereto, and after mixing uniformly, the desired solution is obtained, which is referred to as solution A.
2. configure sodium hypochlorite solution
20 mL of a 10% sodium hypochlorite solution (based on the effective chlorine content) was weighed, 400 mL of water was weighed, and the desired solution was mixed and recorded as Solution B. PS: This solution can also be obtained by mixing 50 mL of 84 disinfectant (effective chlorine content of 4%) with 170 mL of water.
3. Mix solution A with B.
Related links: Luminol
Edited by Suzhou Yacoo Science Co., Ltd.