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StudentStudent InformationInformation NAME :: AKSHAY CHOPRA
CLASS :: XII - A
SCHOOL :: KULACHIHANSRAJ MODELSCHOOL
YEAR :: 2010 11
TEACHERS NAME :: MRS. SUNITATYAGI
BOARD ROLL NO. ::
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IndexIndex
Acknowledgement
Certificate
Aim of the Project
Introduction
Requirements
Theory
Reactions Involved
Observations
Precautions
Bibliography
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AcknowledgementAcknowledgement
I AM EXTREMELY GRATEFUL TO MY
CHEMISTRY TEACHER MRSMRS.. SUNITASUNITA
TYAGITYAGI FOR HER CONSTANT HELP AND
SUPPORT THROUGHOUT THE MAKING OF
MY PROJECT.
I AM EQUALLY THANKFUL TO THE
LABORATORY STAFF FOR PROVIDING ME WITH ALL THE RESOURCES REQUIRED
AND FOR GIVING ME THEIR VALUABLE
INPUT.
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CertificateCertificate
This is to certify that the AkshayAkshay ChopraChopra of classXII A has successfully completed the projecttitled Extraction of Silver from Photographic
Negatives under my supervision.
Mrs. Sunita Tyagi
(Dept. of Chemistry KHMS)
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AIM OF THE PROJECT :: The aim of this project is to extract the
Silver(Ag) metal from the photographic filmsused in the cameras.
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Introduction
o Silver is found in three ways in nature :-
Silver Glance (Ag2S)
Ruby Silver (Ag2S.Sb2O3)
Horn Silver (AgCl)
o Silver is extracted from its sources and is used for many purposes such
as Jewellery, utensils etc.
o On taking X-Rays and photographs can the silver used, be recovered?
Ifyes the how and how much?
And is it profitable?
These are a few vital questions which arose in our minds.
So, as to find an answer to them, we thought of extracting Silver from
the PHOTOGRAPHIC NEGATIVES.
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Requirements ::-
APPARATUS REQUIRED ::
Photographic Negatives
Scissors
Physical Balance
Glass Rod
Funnel
Filter Paper
Wire Gauge
Beakers
Blades
CHEMICALS REQUIRED ::
Sodium Thiosulphate Solution
Conc. Nitric Acid Conc. Ammonium Hydroxide
Formaldehyde
Distilled Water
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TheoryTheory In this case the sources of Silver are the photographic negatives.
The process depends upon the sensitivity of certain silver
compounds to light. A photographic plate on film is covered with
the suspension of AgBr (or some AgCl).
After exposure to gelatin, although there is no visible change, buta latent image is formed on the film. The latent image consists of
small particles of silver which occupy only a part of the grain of
AgBr. The latent image is made visible by immersing the film in a
reducing agent of silver, the grain of AgBr.
The negatives thus formed consist of black metallic silver and
silver bromide. It is made stable to light by dissolving off AgBr
with unchanged Sodium Thiosulphate Solution (Na2S2O3).
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Reactions InvolvedReactions InvolvedI. 3AgCl + 4Na2S2O3 Na5(Ag(S2O3)4) + 3NaCl
II. Ag + 2HNO3 AgNO3 + NO2 + H2O
III. Silver Mirror
2 AgNO3 + 2NH4OH Ag2O + 2NH4NO3 + H2O
Ag2O + HCHO 2Ag + HCOOH
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Now prepare formalin by the following method :-
1 part of formaldehyde + 19 parts of distilled water
Put the scraped mass in concentrated NH4OH and formalin and heat it
for a while.
After heating, filter it twice. A black mass is left behind which containsSilver !!
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Observations ::Observations ::
Initial weight of photographic negatives = 20.12 gm
Final weight of photographic negatives = 17.79 gm
Weight of Silver obtained = 0.16 gm
This excludes 2.17 gm weight on account of useless scraped
mass of the photographic negatives.
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THE WEIGHT OF THE PHOTOGRAPHIC NEGATIVES AS TAKEN BY THE PHYSICALBALANCE SHOULD BE NOTED CAREFULLY.
THE BEAKER CONTAINING PHOTOGRAPHICNEGATIVE SOLUTION SHOULD BE WRAPPED UPTIGHTLY SO THAT DECOMPOSITION CAN OCCUR.
THE BEAKER SHOULD KEPT ASIDE TIGHTLYWRAPPED, FOR AT LEAST 34 DAYS.
THE BLACK MASS SHOULD BE SCRAPED OFFFROM THE NEGATIVES PROPERLY USING A
GLASS ROD.
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Bibliography ::Bibliography ::
I. www.google.com
II. www.wikipedia.com
III. www.chemsitry.about.com
IV. Chemistry NCERT Class XII(Part I) Textbook
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