Luminol experiment Solution A and B are: Solution A and B are mixed and a blue l

Question

Luminol experiment

Solution A and B are:

Solution A and B are mixed and a blue light is observed then disappears.

1. What is the wavelength of this light?

2. What specific molecule is involved in this observed light?

3. What is happening to this molecule as the light is emitted?

4. Why is the light only temporary?

Reactions of this experiment:

Preparation of Solution A (the luminol dianion): Dissolve the first crop of moist luminol (dry weight about 40-60 mg) in 2 mL of 3 M aqueous NaOH solution and 18 mL of water. this reaction can be run at a scale up to five times larger. Preparation of Solution B: Prepare a second stock solution, B, by mixing 4 mL of 3% aqueous potassium ferricyanide, 4 mL of 3% hydrogen peroxide, and 32 mL of water. Prepare this shortly before it will be used, not long in advance.

Explanation / Answer

Luminol experiment

Mixture of solution A of lumniol and solution B of oxidant

The two are mixed together.

From the above data,

a. wavelength of light = 424 nm

b. The luminol dianion is the specific molecule involved in this chemiluminescence experiment of luminol.

c. The dianion relaxes to the ground state as the light is emitted.

d. light emitted is temporary because the electron when relaxed to the ground state does not emit any more light.

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