Science Buddies: "Ask an Expert"

Hello. I am doing an experiment on this topic using red, orange, yellow, blue, and purple UV beads. As I was experimenting, the higher the UV is outside, the longer the colors farther from the ultraviolet zone on the color spectrum take to revert back to colorless. What I don't get is why the yellow beads are the slowest to revert even though they aren't the farthest away from ultraviolet on the visible color spectrum. I have tested this many times and it's always consistent. Is this just an anomaly in the yellow beads or is there a scientific explanation that makes them revert the slowest?
Thank you.

Interesting experiment! Unfortunately, I honestly do not know the answer to your question, but I have located a source that may help you figure out this mystery.

http://cdn.teachersource.com/downloads/ ... UV-AST.pdf

This PDF contains several sections that explain how UV beads work in terms of both physics and chemistry. Temperature is one of the factors that will affect the rate at which the beads change color, but I assume you have kept your temperature constant between testing different beads.

Good luck!

-Karen

Hello I am doing the "Solar-powered Chemistry: Study Chemical Reaction Rates in Ultraviolet Beads" project and I have a question.
I don't understand why the UV beads in the 60 degrees Celsius water are staying white when I take them outside. Is this supposed to happen?
The other beads in the other two cups (20 degrees Celsius and 0 degrees Celsius)are changing color when they're taken outside, and they get pretty dark when they're outside and then when I put them back inside the color fades slowly (slower in the 0 degrees Celsius cup). So I don't understand why they won't even change color at all in the 60 degrees Celsius cup, please help!!!
Thanks

Can someone please urgently help me? I am not able to understand whether I should take the UV beads indoors immersed in water or if they should be taken out. Please help me out. Also, how will I keep the temperatures in each cup constant?

Hi SanjanaRamachandran3456,

I’m assuming that you are working on the project described here:

https://www.sciencebuddies.org/science- ... p088.shtml

The objective of the project is to find out how temperature affects the rate at which the UV beads lose their color. To maintain the different temperatures as they lose color the beads should remain in immersed in water in the 3 different cups after you bring them indoors. The 12-ounce foam cups specified in the procedure should provide enough insulation to keep the temperature reasonably constant during your experiment.

I hope this helps. Please ask again if you have more questions.

A. Norman

isabelllagarcia wrote:Hello I am doing the "Solar-powered Chemistry: Study Chemical Reaction Rates in Ultraviolet Beads" project and I have a question.
I don't understand why the UV beads in the 60 degrees Celsius water are staying white when I take them outside. Is this supposed to happen?
The other beads in the other two cups (20 degrees Celsius and 0 degrees Celsius)are changing color when they're taken outside, and they get pretty dark when they're outside and then when I put them back inside the color fades slowly (slower in the 0 degrees Celsius cup). So I don't understand why they won't even change color at all in the 60 degrees Celsius cup, please help!!!
Thanks

I have the same question but i can not find the experts answer. Please respond. thanks

Hi vfw,

The beads in the hot water should change color when exposed to sunlight. I don’t know why your beads did not work.

Did you heat the water with the beads in it? If so, my suggestion is to try heating the water separately. After heating, immerse a new set of beads (not the ones you heated before) in the water and try exposing to sunlight.

I hope this helps. Please ask again if you have more questions.

A. Norman