Caption: Photochemical decomposition of thionin. In this timelapse demonstration, the intense light causes the thionin, in an acidic solution, to be photochemically reduced by the ferrous or iron (II) ion. Thionin can exist in two forms, the oxidized form (purple), and the reduced form (colourless). When the reducing agent Fe2+ is added to the acidic thionin solution, the thionin molecule, in the presence of intense light, accepts two hydrogen atoms and is thereby reduced to its colourless form. When the light is dimmed, the thionin solution returns to its oxidised purple colour.

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Keywords: 14 seconds or greater, acid, acidic, agent, change, changing, chemical, chemistry, colourless, decomposition, demonstrating, demonstration, education, educational, effect, effects, element, exothermic, experiment, experimental, explosion, explosive, fe2+, ferrous, hydrogen, intense light, ion, iron ii, laboratory, light, oxidation, oxidising, oxidizing, oxygen, photochemical, photochemical decomposition of thionine, photochemically, purple, reacting, reaction, reduced, reducing, reducing agent, reduction, science, solution, thionin, timelapse

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Photochemical reaction

K004/4965 Rights Managed

Downloadable master

Duration: 00:00:29

Frame size: 1920x1080

Frame rate: 25

Audio: No

Format: QuickTime, Photo JPEG 100%, progressive scan, square pixels

File size: 195.7M


Capture format: Sony FS700

Codec: Apple ProRes 422 HQ

Interlaced: Yes

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