UV Beads

Ask questions about projects relating to: aerodynamics or hydrodynamics, astronomy, chemistry, electricity, electronics, physics, or engineering

Moderators: MelissaB, kgudger, Ray Trent, Moderators

UV Beads

Postby brendypendy » Sat Jan 05, 2013 12:53 pm

When I put UV detecting beads in different temperatures of water, the beads that were in water temperatures above 60 degrees C did not change color in the sun, but the beads in water temperatures from 0 to 50 degrees C did. Why did the beads in the hotter water not change color?
brendypendy
 
Posts: 2
Joined: Sat Jan 05, 2013 7:55 am
Occupation: Student 9th grade
Project Question: I was putting UV beads in the sun in different temperatures of water for 1 minute so that the beads would change color and then taking them inside to test how the temperature affected the reaction rate for the beads to change back to their colorless form. I tried putting the beads in water that was 0,10,20,30, 60 and 100 degrees C . When the beads were in the water that was 60 and 100 degrees C they did not react with the UV rays from the sun to change color. Can you tell me why.
Project Due Date: Feb. 1, 2013
Project Status: I am finished with my experiment and analyzing the data

Re: UV Beads

Postby rmarz » Sat Jan 05, 2013 5:14 pm

brendypendy - I'm not an expert on UV beads, but was curious when I saw your post so I did a little research. The fundamental action is that when the colorless beads are subjected to UV light source, certainly like the sun, or perhaps a flourescent light, the pigments will be activated and turn colored. When the beads are returned to a non-UV environment, they will revert to the colorless state. In reading one of the bead suppliers descriptions it states:

"Although UV light is needed to excite the molecule to form the high-energy planar structure, heat from the surroundings provides the activation energy to change the molecule back to its colorless structure. If colored beads are placed in liquid nitrogen, they will not have enough activation energy to return to the colorless form".

That suggests that there is a thermal aspect to how these beads act and reverse their state. Extreme cold prevents them for reverting back to colorless. Higher temperatures may have the reverse effect, preventing the beads to transition to a colored state. Perhaps the higher temperatures you used caused the beads to be temporarily insensitive to the UV radiation. If you cool the beads, do they then change color when exposed to UV light? In the experiments I looked at on the WEB, they had not demonstrated the effect of the warmer beads to be insensitive, or the need to keep the beads cooler.

Rick Marz
rmarz
Expert
 
Posts: 440
Joined: Sat Oct 25, 2008 1:26 pm
Occupation: Technology Consultant
Project Question: n/a
Project Due Date: n/a
Project Status: Not applicable

Re: UV Beads

Postby brendypendy » Sun Jan 06, 2013 10:32 am

Thanks, that's sort of what I was thinking. Can't find an exact answer, but this does make sense. After being cooled, the beads did turn colour when placed in the sun.
brendypendy
 
Posts: 2
Joined: Sat Jan 05, 2013 7:55 am
Occupation: Student 9th grade
Project Question: I was putting UV beads in the sun in different temperatures of water for 1 minute so that the beads would change color and then taking them inside to test how the temperature affected the reaction rate for the beads to change back to their colorless form. I tried putting the beads in water that was 0,10,20,30, 60 and 100 degrees C . When the beads were in the water that was 60 and 100 degrees C they did not react with the UV rays from the sun to change color. Can you tell me why.
Project Due Date: Feb. 1, 2013
Project Status: I am finished with my experiment and analyzing the data


Return to Grades 9-12: Physical Science

Who is online

Users browsing this forum: Bing [Bot] and 8 guests