Science Buddies: "Ask an Expert"

Hi,


I am undergoing an experiment which involves UV beads and how its colour changes with varying temperatures. For this experiment, I am trying to figure out what the exact photochromic chemical is present in the beads, I know some use napthopyran but what are the one's used specifically on the website?

Furthermore, I am attempting to find the activation energy of napthopyran if it is indeed the chemical present in UV beads? I have attempted to search it up online but could not find a value for the Ea. How can I find this value?


Thank you in advance.

Hi,

I checked the beads on Carolina Bio and they do not say what the photochromic chemical is (http://www.carolina.com/solar-energy/so ... n=uv+beads). Did you call them and ask what the chemical is? They should be able to tell you.

It might be one of the naphthopyrans, but determining the E-act is difficult for a complex heterocyclic molecule like that. If you had a variable UV source and a meter that measured UV energy in joules/m2 you could probably calculate a minimum energy of activation just based on threshold of color change, but I've never tried to do that.

Have you posted your question on the physical sciences forum? The experts there are more knowledgeable about chemistry than those in the life sciences.

Good luck!

Sybee

Thank you for the advice!