November 04, 2024, 03:37:47 PM
Forum Rules: Read This Before Posting


Topic: Reactions that are affected by light rays?  (Read 5698 times)

0 Members and 1 Guest are viewing this topic.

Offline ade93

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Reactions that are affected by light rays?
« on: February 14, 2011, 12:59:36 PM »
Hi folks!, I'm asking you guys 'cause my teacher is not allowed to help me  ;)  I couldn't find anything on Google so I hope you will help me :)
  Does any of you know any reactions that are affected by light rays? My extended essay will mainly be about that; to what extent do light rays have on 'the formula the reactants (which is for now on unknown)'
 Write down all reactions you can figure out and in hierarchy (the easiest to make should be first).

 The reaction should be not too hard to make because I'm still an highschool student.

Offline DevaDevil

  • Chemist
  • Full Member
  • *
  • Posts: 690
  • Mole Snacks: +55/-9
  • Gender: Male
  • postdoc at ANL
Re: Reactions that are affected by light rays?
« Reply #1 on: February 14, 2011, 01:20:59 PM »
well, think of all reactions that are involved in photography

Offline ade93

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Re: Reactions that are affected by light rays?
« Reply #2 on: February 14, 2011, 01:31:29 PM »
lol, I have never thought about that before so I cant come up with any reactions in photography haha, please tell me :)

Offline DevaDevil

  • Chemist
  • Full Member
  • *
  • Posts: 690
  • Mole Snacks: +55/-9
  • Gender: Male
  • postdoc at ANL
Re: Reactions that are affected by light rays?
« Reply #3 on: February 14, 2011, 03:38:46 PM »
do some searches yourself and you might find sites such as this one.




Offline Enthalpy

  • Chemist
  • Sr. Member
  • *
  • Posts: 4036
  • Mole Snacks: +304/-59
Re: Reactions that are affected by light rays?
« Reply #4 on: February 14, 2011, 09:08:51 PM »
One commercial glue sold for PMMA (a plastic, one commercial name for it being Plexiglas) is just the monomer, MMA. It polymerizes at near-UV light, for instance under a fluorescent lamp, or at Sunlight, quickly - so keep it in the dark, use it in red light before curing.

Easy to use. But take great care to ventilate well, as the vapours are very uncomfortable to the eyes.

By the way, the first machines for stereolithography (or rapid prototyping, see Wiki) worked on MMA. More materials can be used meanwhile, including powders sintered by stronger light.

Offline Enthalpy

  • Chemist
  • Sr. Member
  • *
  • Posts: 4036
  • Mole Snacks: +304/-59
Re: Reactions that are affected by light rays?
« Reply #5 on: February 15, 2011, 10:44:37 AM »
Sunlight decomposes most plastics.

More easily observed on a thin film, like a plastic bag. Few weeks in Summer suffice to make it brittle.

It's one stop-or-go criterion to choose a plastic for the exposed parts of a satellite; UV is far worse to most plastics than ionizing radiations on a satellite.

-----

You could also think of melanin pigments, but the experiment is uncomfortable.

Sponsored Links