Question

Photochromic sunglasses, which darken when exposed to light, contain a small amount of colourless AgCl(s) embedded in the glass. When irradiated with light, metallic silver atoms are produced and the lass darkens.
`AgCl(s)toAg(s)+Cl`
Escape of chlorine atoms is prevented by the rigid structure of the glass and the reaction therefore, reverses as soon as the light is removed. if 310 kJ/mol of energy is required to make the reaction proceed, what wavelength of light is necessary.?

Answer 1

Energy per mole=Energy of one Einstein,
i.e., energy of one mole quanta
`=(Nhc)/(lamda)`
`therefore310xx1000=(6.023xx10^(23)xx6.626xx10^(-34)xx3xx10^(8))/(lamda)`
`lamda=3.862xx10^(-7)m=3862xx10^(-10)m=`3862Ã…