estimation of ferric in magnetic tapes

8/8/2019 Estimation of Ferric in magnetic Tapes

http://slidepdf.com/reader/full/estimation-of-ferric-in-magnetic-tapes 1/20



© Copyright, 2011 Elsea publishing Ltd.- 1 -

ESTIMATION

OF

FERRIC

INMAGNETIC TAPES

V.Arun SabhapathiJ.DharanidaranS.Tarun Cousik




ContentsBona fide

3Acknowledgement

4Introduction

5Theory

8Experiment

12Calculation

16References

18




BOBOBOBONA NA NA NA FIFIFIFIDEDEDEDE A. Krishnan

HEAD OF THE CHEMISTRY DEPARTMENTP S SENIOR SECONDARY SCHOOL

MYLAPORE, CHENNAI -600004

I hear by certify that the work done in this project entitled Estimation of Ferric in

Magnetic Tapes is a bona fide work done by V.Arun Sabhapathi,

J.Dharanidaran and S.Tarun Cousik. Roll no:

______________________________________________________________________________

in the department of Chemistry of P S Senior Secondary School under my supervision,

during the academic year 2010-2011.

I certify that the work represents independent work on the part of the candidate.

DATE: SIGNATURE:

Submitted for the practical examination held in the school centre on ___________________

INTERNAL EXAMINER EXTERNAL EXAMNIER




ACKNOWLEDGEMENT

We would like to thank Mrs. R.Sundari, (M.Sc., B.Ed.),

for her continued support and encouragement towards the

completion of our project.

We also express our gratitude to Mrs. B.Jayalakshmi for

her invaluable assistance.




INTRODUCTION

The Tape

The tape itself is actually very simple. It consists of a thin plastic base material, and

bonded to this base is a coating of ferric oxide powder. The oxide is normally mixed witha binder to attach it to the plastic, and it also includes some sort of dry lubricant to avoid

wearing out the recorder.

Iron oxide (FeO) is the red rust we commonly see. Ferric oxide (Fe2O3) is another oxide

of iron. Maghemite or gamma ferric oxide is a common name for the substance.

This oxide is a ferromagnetic material, meaning that if you expose it to a magnetic field it

is permanently magnetized by the field. That ability gives magnetic tape two of its most

appealing features:

• You can record anything you want instantly and the tape will remember what

you recorded for playback at any time.

• You can erase the tape and record something else on it any time you like.

There are two parts to any audio magnetic recording system: the recorder itself (which

also acts as the playback device) and the tape it uses as the storage medium.




*

If one were to look inside a compact cassette, you will find that it is a fairly simple

device. There are two spools and the long piece of tape, two rollers and two halves of a

plastic outer shell with various holes and cutouts to hook the cassette into the drive. There

is also a small felt pad that acts as a backstop for the record/playback head in the tape

player. In a 90-minute cassette, the tape is 135 meters long.

Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating

on a long, narrow strip of plastic non biodegradable polymer.

It was developed in Germany, based on magnetic wire recording.

Devices that record and play back audio and video using magnetic tape are tape recorders

and video tape recorders. A device that stores computer data on magnetic tape is a tape

drive (tape unit, streamer).

Magnetic tape revolutionized broadcast and recording. When all radio was live, itallowed programming to be prerecorded. At a time when gramophone records were

recorded in one take, it allowed recordings in multiple parts, which mixed and edited with

tolerable loss in quality.




It is a key technology in early computer development, allowing unparalleled amounts of

data to be mechanically created, stored for long periods, and to be rapidly accessed.

Today, other technologies can perform the functions of magnetic tape. In many cases

these technologies have replaced tapes.

Over years, magnetic tape can suffer from deterioration called sticky-shed syndrome,

caused by absorption of moisture into the binder of the tape, it can render the tape

unusable.

Nowadays, due to incoming of products like Compact Disks(CD), portable disks and

Universal Serial Bus drives(USB). They have shown a dominant increase in sales

throughout the world, tapes have been neglected and they pose a serious threat to theenvironment as they are dumped in large numbers especially in developing countries like

India ,Pakistan, Bangladesh and China .

Extraction minerals such as iron, chromium,and nickel from these dumped tapes are

considered to be profitable business and also a environmental friendly measure.




THEORY




IRON(III) OXIDE

Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is of

one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is

rare, and iron(II,III) oxide (Fe3O4), which also occurs naturally as the mineral magnetite.

As the mineral known as hematite, Fe2O3 is the main source of the iron for the steel

industry. Fe2O3 is paramagnetic, reddish brown, and readily attacked by acids.

Properties

Molecular formula Fe2O3

Molar mass 159.69 g/mol

Appearance red-brown solid

Odor

odorless

Density 5.242 g/cm

3, solid

Melting point1566 °C (1838 K) decomp.

Solubility in water insoluble

Structure

Crystal structure rhombohedral

Thermo chemistry

Std enthalpy of formation∆f H

o298

−825.50




Para magnetism

Para magnetism is a form of magnetism that occurs only in the presence of an externally

applied magnetic field. Paramagnetic materials have a relative magnetic permeability

greater or equal to unity, i.e. a positive magnetic susceptibility, and hence are attracted to

magnetic fields.

Delocalization

In many metallic materials the electrons are itinerant, i.e. they travel through the solid

more or less as an electron gas. This is the result of very strong interactions (overlap)

between the wave functions of neighboring atoms in the extended lattice structure. The

wave functions of the valence electrons thus form a band with equal numbers of spins up

and down. When exposed to an external field only those electrons close to the Fermi level

will respond and a small surplus of one type of spins will result. This effect is a weak form of paramagnetic known as Pauli-paramagnetic. The effect always competes with a

diamagnetic response of opposite sign due to all the core electrons of the atoms. Stronger

forms of magnetism usually require localized rather than itinerant electrons. However in

some cases a band structure can result in which there are two delocalized sub bands with

states of opposite spins that have different energies. If one sub band is preferentially

filled over the other, one can have itinerant ferromagnetic order. This usually only

happens in relatively narrow (d-)bands, which are poorly delocalized.

s and p electrons

Generally, strong delocalization in a solid due to large overlap with neighboring wave

functions tends to lead to pairing of spins (quenching) and thus weak magnetism. This is

why s- and p-type metals are typically either Pauli-paramagnetic or as in the case of gold

even diamagnetic. In the latter case the diamagnetic contribution from the closed shell

inner electrons simply wins from the weak paramagnetic term of the almost free

electrons.

d and f electrons

Stronger magnetic effects are typically only observed when d- or f-electrons are involved.

Particularly the latter are usually strongly localized. Moreover the size of the magneticmoment on a lanthanide atom can be quite large as it can carry up to 7 unpaired electrons.

This is one reason why superstrong magnets are typically based on lanthanide elements

like neodymium or samarium.




Molecular localization

Of course the above picture is a generalization as it pertains to materials with an

extended lattice rather than a molecular structure. Molecular structure can also lead tolocalization of electrons. Although there are usually energetic reasons why a molecular

structure results such that it does not exhibit partly filled orbital’s (i.e. unpaired spins),

some non-closed shell moieties do occur in nature. Molecular oxygen is a good example.

Even in the frozen solid it contains di-radical molecules resulting in paramagnetic

behavior. The unpaired spins reside in orbital’s derived from oxygen p wave functions,

but the overlap is limited to the one neighbor in the O2 molecules. The distances to other

oxygen atoms in the lattice remain too large to lead to delocalization and the magnetic

moments remain unpaired.

Method used for Quantitative estimation

Since direct estimation of ferric ion through titration is not possible The Fe3+ ions in

Fe2O3 are reduced to Fe2+ using a reducing agent of stannous chloride in an acidic

medium of HCl.

Once all the Fe3+ ions are reduced to Fe

2+ ions, this solution is boiled in HCl medium

and titrated against the potassium dichromate solution and for a constant volume of

potassium dichromate titrated, a small volume of ferricyanide is added to validate thepresence of Fe

2+.The appearance of Prussian blue color validates the process.




EXPERIMENT




AIM:-

To estimate the content of ferric iron present in the whole of the given ferric oxidesolution by external indicator method, given we are supplied with pure crystals ofpotassium dichromate (K2Cr2O7).

PRINCIPLE :-

Ferric Iron is in the highest oxidation state. It is reduced to ferrous iron titrating with the

standard dichromate solution. The reduction is carried out by before the use of stannous

chloride solution and concentrated HCl acid. Excess of stannous chloride is removed by

Mercuric chloride. Potassium ferricyanide is used as the external indicator.

Equivalent mass of ferric iron = 55.85 (Atomic mass of Iron).

Procedure

Preparation of standard Potassium dichromate Solution

1. Accurately about 1.25g of Potassium dichromate of AR quality is weighed in a

chemical balance.

2. It is transferred into 250 ml flask and the solution is made up to the mark.

3. The solution is shaken well to get a homogeneous solution.

4. Solution of the known strength is taken in the burette after a thorough rinsing with

it.

Extraction of ferric from tape

1. The tape is dissolved in sufficient quantity of acetone.

2. Excess acetone is removed by keeping the solution in water bath.

3. The dry left over black powder is taken in a volumetric flask.




Stage I: Reduction of Ferric Iron to Ferrous Iron

1. The given ferric Iron powder is made up to 100 ml in a volumetric flask.

2. It is thoroughly shaken to get a homogeneous solution.

3. Exactly 20 ml of the solution is pipette out into a clean 250 ml (preferably

corning) beaker.

4. About 5 ml of conc. HCl is added to it & is heated to boiling.

5. Freshly prepared stannous chloride solution is added in drops to the hot solution

until just the yellow colour of the solution disappears.

6. A few more drops of Stannous Chloride solution are added in excess.

7. The solution is diluted to about 150 ml and cooled to 200C and then 10 ml of a

saturated solution of mercuric chloride is added to it. A thin silky white precipitate

is formed in the solution.

State II: Titration of Ferrous Iron Solution Vs Standard Dichromate Solution:

1. The reduced turbid solution containing ferrous iron is mixed with about 20 ml of dilute sulphuric acid.

2. About 10 ml standard potassium dichromate solution is added from the burette.

3. During the course of the titration, the solution in the conical flask or beaker is

stirred well.

4. A drop of the solution in the beaker is treated with a droplet of potassium

ferricyanide solution placed on a porcelain tile. (Allow a few minutes to observethe colour change).

5. If the solution turns blue in colour, it indicates the presence of ferrous iron in

solution.




6. The titration is continued by adding 1 ml every time and then testing a drop of

solution in the beaker with ferricyanide as above. The addition of dichromate

solution is continued until a drop of the solution gives a bottle green color with

ferricyanide solution.

7. The burette reading is noted. It gives the range in which the end point occurs.

8. To find the accurate value, in the second experiment, the standard dichromate

solution is run in without testing till one ml before the range fixed. At this

juncture, dichromate solution is added in drops after testing the solution from time

to time with ferricyanide solution until the solution gives no colour with theindicator.

9. The titration is repeated to get concordant values. From the volume of dichromate

solution the strength of ferric iron solution, and hence its amount is calculated.

Result

The amount of ferric iron present in the whole of the given solution = .38 g




NOTE :-

(1) It is sufficient to prepare 0.2% potassium ferricyanide indicator solution to be used

in the titration.

(2) To avoid error due to volume loss, pointed glass rod must be used to test the

solution. The glass rod is washed with distilled water every time before use.

(3) The indicator in small drops may be placed on a porcelain tile with depression.

(4) The indicator solution should not contain ferrocyanide solution. Otherwise it

readily gives blue colour with ferric iron present in the solution.

Calculation

Weight of K2Cr2O7 crystals in 250 ml of the solutions = 0.15625 g

Equivalent mass of oxalic acid = 49.03

Gram equivalents = Mass in g

Eq. mass

= 0.003186

Normality of the standard K2Cr2O7 solution = Gram equivalents of the solute

Volume of solution in liters

= 0.003186

.250

NK2Cr2O7 = 0.1




Volume of K2Cr2O7 solution consumed in the reaction (V1) = 13.8 ml

Volume of Fe+3

iron solution (V2) = 20 ml

Strength of Fe

+3

iron solution (N2) = ?

∴ V1 x N1 = V2 x N2

N2 = V1 x N1

V2

= 13.8 ml x 0.1

20N

Fe+3

solution = 0.069Amount of ferric iron present in the whole of the given solution =

Normality x Eq. Mass of the Fe+3

10

= 0.069 x 55.85

10

= 0.385365 g

Weight of tape with the plastic disk = 10.2039 g

Weight of the plastic disk = 0.9 g

∴ Weight of the tape = 9.3039 g

% composition of ferric oxide in tape = 0.385365 x 100

9.3039

= 4.1419 %




Bibliography

NameNameNameName Link Link Link Link

WIKIPEDIA

Iron(III) oxide http://goo.gl/BYZ7X

Magnetic tape http://goo.gl/4UjXJ

Para magnetism http://goo.gl/yQXlN

Iron oxide http://goo.gl/s7Scm

ADOBE

Acrobat http://goo.gl/I94Zz

Photoshop http://goo.gl/yfngO

GOOGLE

Search http://google.com

Documents editing & storage http://docs.google.com

CLIR

Magnetic Tape Storage and Handling http://goo.gl/usQX2



How Stuff Work

How Tape Recorders Work http://goo.gl/iBDPd

Books

Basic principles of practical chemistry

By

V.Venkateshwaran

R.Veeraswamy

A.R.Kulandaivelu

http://goo.gl/VF9p1