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Name: Azhar
Status: student
Grade: n/a
Country: Pakistan
Date: February 2009


Question:
Why do we keep silver nitrate in amber bottle?



Replies:
Silver Nitrate is photo-sensitive - i.e. it will decompose under the action of light. It is this property that made silver nitrate the preferred base for black and white photographs for the first 70 years or so.

The amber bottle will limit the amount and the range of light which enters the bottle - reducing the extend of the reaction.

When exposed to light the silver nitrate decomposes to produce microscopic grains of silver, which appear black.

The reaction equation is 2AgNO3?2Ag+2NO2+O2.

Nigel Skelton
Tennant Creek High School
AUSTRALIA


Azhar,

Silver ions are sensitive to light. Fugi and Kodak coat their photographic films with silver salts. When light hits the film, the silver changes to a solid. We store silver nitrate in amber bottles to reduce the amount of light that interacts with the silver ions. (I keep my class room silver nitrate solution in amber bottles, in a cardboard carton inside a closet. I only take out the solutions for specific labs -- than they go back in the closet. I have had some of the solutions for more than 5 years.)

Warren Young


Silver ion undergoes a photochemical reduction to silver metal. So silver nitrate, in the presence of light, will darken. In solution the particle size of the silver metal particles is so small the solution darkens. Solid silver nitrate in the presence of light just turns dark due to the presence of tiny particles of silver metal. Be aware that this photochemical reaction is the basis of photographic film and paper.

In these days of digital cameras, traditional photographic film and paper are much more rare than in the past.

Vince Calder


If I remember correctly there may be a couple of reasons.

First, silver nitrate is a corrosive and an oxidizer. I believe it can react with some forms of plastic (and hence the reason to store it in a glass bottle). Chemicals that are stored in amber (or dark) bottles are often sensitive to light. Silver nitrate also falls into this category. So it should be in an appropriate dark glass container.

Michael S. Pierce



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