THE CHEMISTRY OF FILM PHOTOGRAPHY

Transcript of Chemical Reaction of Film Photography




Decomposition & Silver Chloride 

Decomposition is a type of chemical reaction and it may be defined as the reaction in which a single compound splits into two or more simple substances under suitable conditions. It is just the opposite of the combination reaction.



A blank roll of film

 Silver chloride is used for photography. The film used to take pictures is coated with silver crystals. It is a decomposition reaction and only reacts with light. In darkness and certain light it will stay normal. 


Citations
http://wiki.answers.com/Q/What_chemical_reaction_takes_place_in_photography?#slide=2

http://amrita.olabs.co.in/?sub=73&brch=3&sim=80&cnt=1

http://www.chemistryislife.com/t-1


The Reaction 
Silver Chloride use to be widely used for flash in old time photography. When Silver Chloride is exposed to light, it decomposes. When film containing Ag+ and Cl- is exposed to light energy, the image in front or exposed to the film is then transferred on, like a print/copy of the object. The only time this cannot occure is when light is not present. Only Red and Black lights are able to be around Silver Chloride without making the substance react. 


The Type of Chemical Reaction
For Silver Chloride as a chemical, the oxidation state for Ag(Silver) would be a +1 charge and the state for Cl(Chlorine) is -1. For the pure elements, both charges for the two would be 0.

The equation for the decomposition reaction is
AgCl2---> Ag + Cl2
The chemical formula is just AgCl


Physical Properties: Photographic film is a strip or sheet of transparent plastic film base coated on one side with a gelatin emulsion containing microscopic small light sensitive silver halide crystals
Colors of film can be black and white, colored, red, green, blue
Temperature: The light is a heated bulb
Catalyst: Example of a photography catalyst
When the photo-catalyst,Tio2 captures ultraviolet light it forms activated oxygen from water or oxygen in the air.
A decomposition reaction is just when one compound breaks down to create two or more simpler substances
general form: AB---> A + B
Silver Chloride is a decomposition reaction

Electron ejected from chlorine (Oxidation): 

Ag+ + Cl- + light energy → Ag+ + Cl + 1 electron 

Electron captured by silver (Reduction): 

Ag+ + 1 electron → Ag (metal) 

Silver chloride is apart of the decomposition reaction family. It is used for making prints in the photography world. Film is actually coated with silver. It is very reactive with light and decomposes when is exposed. The general form for decomposition is: AB---> A + B 
Stay Rad.








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