Chem Project 2003

8/7/2019 Chem Project 2003

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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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Chem Project 2003

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