Intro: Demonstrating Simple Photochemistry With Silver Chloride
We show the chemistry of photography using silver chloride that we make ourselves from table salt and silver nitrate.
Silver chloride has the interesting property that it reacts to light. This photosensitive chemical will decompose into dark silver powder and chlorine.
To make it, just mix one gram of silver nitrate made in our previous video ( http://www.youtube.com/watch?v=d6hPgGV_qAg ) and half a gram of table salt in separate quantities of water. Then mix the two solutions with shaking, this forms silver chloride. Then let it stand for five minutes. This will cause the silver chloride to settle to the bottom. After five minutes pour off the extra liquid. Spread out the silver in a layer onto a piece of paper. Let it dry in darkness as you don't want the light to expose it before you're ready. Once it is dry, place a stencil or template of something you want "photographed" over the silver chloride. You might want to weigh it down with a piece of glass.
When you're ready, shine a strong light onto it for ten minutes or so. The silver chloride will darken in the areas that are exposed to light. Remove the glass and template and you will have a negative photo of what you placed over it.
The image won't keep forever, eventually the whole thing will darken.
This is ofcourse a very simple experiment and modern photography is far superior, including the use of darkroom techniques, developer solutions and means of 'fixing' the image. The above demonstration is just that, a demonstration, and is not meant to offend experts in the field of photography and photochemistry.
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