Question

in your own words, describe how Transition lenses are an example of Le Chatelier's principle.

What is being added or removed?

Is it a product or reactant in the chemical reaction? How does this relate to Le Chatelier's principle?

How does this effect the color of the lenses?

In your own words, explain how Transition lenses are an example of Le Chatelier's principle. In your answer, address: a. What is being added or removed? b. Is it a product or reactant in the chemical reaction? How does this relate to Le Chatelier's principle? C. How does this effect the color of the lenses?

Answer 1

Solution - 1: Le Chatelier Principle of transition lenses: They are transparent to visible light without significant ultraviolet component, which is normal for artificial lighting. In another sort of technology, organic photochromic molecules, when exposed to ultraviolet (UV) rays as in direct sunlight, undergo a chemical process that causes them to change shape and absorb a significant percentage of the visible light, i.e., they darken. These processes are reversible; once the lens is removed from strong sources of UV rays the photochromic compounds return to their transparent state. O O AgCl is embedded in transition lenses. Organic photochromic molecules (for example oxazines and naphthopyrans) are added to achieve the reversible darkening effect.

(b) It is reactant in the chemical reaction. In the presence of UV-light (wavelengths of 320-400 nm), electrons from the glass combine with the colorless silver cations to form elemental silver. Because elemental silver is visible, the lenses appear darker. Cl--> Cl + e- Ag+ + e--> Ag Back in the shade, this reaction is reversed. The silver returns to its original ionic state, and the lenses become clear. Cu^2+ + Ag -> Cu+ + Ag+ (c) The substance that is being added in transition lenses affects the color of the same. Because different transitions happen with the molecules. Electrons being excited to the higher state energy level and when they come back to ground state, they emit energy of different wavelengths.