Apologies in advance as I am not a science person by any definition. By most, I'm probably not a person but we'll let that be.
I am studying the notion of "change" in things and focusing on chemical change. Could someone please let me know if:
the change in the color of a photogray (photosensitive, photochromic) lens is a "chemical" change?
the change in a baby's diaper when it gets wet is a chemical change (and if it is similar in any nature to the change in #1) and if that is the same as the change in a pregnancy test or a urinalysis stick
if the change in a thermochromic/temperature sensitive item (a beer can that changes color in the cold, a color changing thermometer or spoon or mood ring ) is the same type of chemical change
Sorry if this is too much for one question, or if it can't be explained to a lay person, but I appreciate any responses. I'm too newbie on this board to post all the links as links so the questioned items are connectable through the list of urls.
-----edit--------------- The question of "chemical" change would be, in my mind different from "physical" but I don't know if that distinction comes into play here, or is an issue when the change is permanent or temporary.