A Levels Chemistry

Photochromic glass, used for sunglasses, darkens when exposed to bright light and becomes
more transparent again when the light is less bright. The depth of colour of the glass is related to
the concentration of silver atoms.
The following reactions are involved.
reaction 1
Ag* + Cl Ag + Cl
reaction 2
Cu* + Cl → Cu²* + CI-
reaction 3
Cu²+ + Ag → Cu* + Ag*
Which statement about these reactions is correct?
A Cu' and Cu²* ions act as catalysts.
B Cu' ions act as an oxidising agent in reaction 2.
Reaction 2 is the one in which light is absorbed.
D Ag* ions are oxidised in reaction 1.


Transition Elements | 2009 - O/N - 9701/11 | Q11