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IS 9506 (1980): Method for determination of sulphate(volumetric) [CHD 1: Inorganic Chemicals]

IS : 9506 - 1980

Indian Standard METHOD FOR DETERMINATION OF

SULPHATE ( VOLUMETRIC )

© Copyright 1980

I N D I A N S T A N D A R D S I N S T I T U T I O N MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW D E L H I 110002

Gr 2 July 1980

UDC 543.24 : 546.226

AMENDMENT NO. 1 DECEMBER 1990 TO

IS 9506 : 1980 METHOD FOR DETERMINATION OF SULPHATE ( VOLUMETRIC )

( Page 5, clause 3.2.2, first sentence ) — Substitute the following for the existing sentence: 'Weigh about 1 g of the ground sample accurately, dissolve in 10 ml of concentrated hydrochloric acid and evaporate to dryness.'

( Page 6, clause 3.2.3 ) — Substitute the following for the existing matter:

'Sulphate ( as SO4 ), percent by mass = × 0.096 × 100

where V1 = volume in ml of EDTA solution added, V2 = volume in ml of magnesium chloride solution required for back

titration, M1 = molarity of EDTA solution, M2 = molarity of magnesium chloride solution, and M = mass in g of the sample taken in the aliquot of the solution

for the test.'

( CHD 1 )

Printed at Printwell Printers, Delhi, India

IS : 9506 - 1980

Chemical Standards Sectional Committee, CDC 1 Chairman

DR H. L. BAMI

Members

Representing Central Forensic Science Laboratory (Central Bureau

of Investigation ), New Delhi

DR K. NARAYANASWAMY (Alternate to Dr H. L. Bami)

AGRICULTURAL MARKETING ADVISER

Central Agmark Laboratory ( Ministry of Agricul­ture ), Nagpur

SHRI T. V. MATHEW ( Alternate ) SHRI B. N. BHATTACHARYYA SHRI V. M. BHUCHAR SHRI D. S. CHADHA

Geological Survey of India, Calcutta National Physical Laboratory ( CSIR ), New Delhi Directorate General of Health Services, New Delhi

SMT DEBI MUKHERJEE ( Alternate ) DR M. S CHADHA SHRI R. S. CHATIM CHEMIST & METALLURGIST,

SOUTH CENTRAL RAILWAY, SECUNDERABAD

ASSISTANT D I R E C T O R ( MET ), RDSO, LUCKNOW ( Alternate )

SHRI D. R. GUPTA

Bhabha Atomic Research Centre, Bombay Municipal Corporation of Greater Bombay Railway Board ( Ministry of Railways )

Central Revenues Control Laboratory ( Ministry of Finance ), New Delhi

SHRI KESHAV PRASAD ( Alternate) DR R. K. GUPTA

SHRI N. S. BIRDIE ( Alternate ) SHRI C. HINGARH

SHRI OM PRASAD (Alternate) JOINT DIRECTOR ( CHEM )

DEPUTY DIRECTOR ( MCL ) ( Alernate )

JOINT DIRECTOR ( C H E M / T D )

Shriram Institute for Industrial Research, Delhi

The Century Spg & Mfg Co Ltd, Bombay

Department of Industries & Commerce, Government of Tamil Nadu, Madras

Directorate of Industries, Government of Maha­rashtra, Bombay

ASSISTANT DIRECTOR ( QM ) ( Alternate )

( Continued on page 2 )

© Copyright 1980 INDIAN STANDARDS INSTITUTION

This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.

Indian Standard METHOD FOR DETERMINATION OF

SULPHATE ( VOLUMETRIC )

IS : 9506 - 1980

(Continusd from page 1) Members

DR B. N. MATTOO

DR M. S. MADIWALE DR P. R. PABRAI

SHRI J. K. PATWA SHRI D. RAMAMURTHY

Representing Maharashtra State Forensic Science Laboratoty,

Bombay ( Alternate )

Central Indian Pharmacopoeia Laboratory, Ghaziabad

Sarabhai M. Chemicali, Vadodara Bharat Heavy Electricals Ltd, Hyderabad

SHRI M. B. UNNI ( Alternate I ) SHRI S. K. BOSE ( Alternate II )

DR G. RAMANA RAO Indian Drugs & Pharmaceuticals Ltd, New Delhi SHRI RANGASWAMY ( Alternate )

DR M. P. SAHAKARI Italab Pvt Ltd, Bombay SHRI S. S. HONAVAR ( Alternate )

DR B. R. SANT Regional Research Laboratory (CSIR) , Bhuba-neshwar

DR T. P. PRASAD ( Alternate ) SHRI K. C. SEAL National Test House, Calcutta

SHRI P. K. PAIN ( Alternate ) DR A. K. SEN Ministry of Defence ( DGI )

SHRI N. S. SENGAR ( Alternate ) SHRI H. M. SHAIKH DR V. SRINIVASAN

National Organic Chemical Industries Ltd, Bombay Glaxo Laboratories ( India ) Ltd, Bombay

DR S. V. VORA ( Alternate ) DR HARI BHAGWAN,

Director (Chem ) Director General, ISI ( Ex-officio Member )

Secretary SHRI N. K. SHARMA

Deputy Director ( Chem ), ISI

IS : 9506 - 1980

Indian Standard METHOD FOR DETERMINATION OF

SULPHATE (VOLUMETRIC)

0 . F O R E W O R D 0.1 This Indian Standard was adopted by the Indian Standards Institution on 27 May 1980, after the draft finalized by the Chemical Standards Sectional Committee had been approved by the Chemical Division Council. 0.2 The volumetric methods for determination of sulphate given in this standard are useful when sulphate is present in semi-micro amounts rang-ing from a fraction of 1 mg to about 5 mg, and in macro amounts ranging from 5 to 100 mg.

0.2.1 The gravimetric method for the determination of sulphate is covered in IS : 2317-1975*. 0.3 This standard intends to achieve uniformity in details of the method prescribed in various Indian Standards. 0.4 In reporting the result of a test or analysis made in accordance with this standard) if the final value, observed or calculated, is to be rounded off, it shall be done in accordance with IS : 2-1960†.

1. SCOPE 1.1 This standard prescribes volumetric methods for the determination of sulphate in semi-micro and macro amounts.

2. QUALITY OF REAGENTS 2.1 Unless specified otherwise, pure chemicals and distilled water ( see IS : 1070-1977‡ ) shall be employed in tests.

NOTE — 'Pure chemicals' shall mean chemicals that do not contain impurities which affect the results of analysis.

*Method for gravimetric determination of sulphates ( first revision ). †Rules for rounding off numerical values ( revised ). ‡Specification for water for general laboratory use ( second revision ).

3

IS : 9506 - 1980

3. METHOD 3.1 Direct Method

3.1.0 Outline of the Method — The sulphate is titrated against a standard barium solution. Barium sulphate precipitates out; the end point is detected by the appearance of a blue green colour formed by barium sulphonazo III complex. Carbonates, nitrates and chlorides do not interfere.

3.1.1 Reagents 3.1.1.1 Acetone 3.1.1.2 Standard sulphuric acid — 0.1 N ( see 56 of IS : 2316-1968* ). 3.1.1.3 Standard sulphuric acid — 0.01 M. Dilute 20 ml of 0.1 N

sulphuric acid to 100 ml in a volumetric flask. 3.1.1.4 Standard barium perchlorate solution — 0 01M. Suspend about 2.2 g

of barium carbonate in little water, add perchloric acid drop bv drop till evolution of carbon dioxide ceases. Heat the solution to boil off carbon dioxide. Cool and dissolve in 500 ml of water in a one-litre volumetric flask. Add 500 ml of acetone to make up to one litre. Standardize against 0.01 M sulphuric acid.

3.1.1.5 Sulphonazo III indicator solution — 0.02 percent aqueous solution ( m/v ).

3.1.2 Procedure — Take an aliquot of the sulphate solution that may contain up to about 5 mg of sulphate. Adjust the pH between 5 to 5.5. Add an equal volume of acetone and 2 to 3 drops of sulphonazo III indicator solution Titrate against barium perchlorate solution. With just a few drops of the titrant the colour seems to change to green or light blue, but returns to red on further shaking and a white precipitate/turbi-dity of barium sulphate settles out. Continue titration with shaking till the colour changes to light blue or green. One millilitre of barium perchlorate solution is equivalent to 0.96 mg of sulphate.

3.1.3 Calculation

Sulphate ( as SO4 ), percent by mass =

where V = volume in ml of barium perchlorate solution, and

M = mass in mg of the material taken for the test. *Methods of preparation of standard solutions for colorimetric and volumetric

analysis ( first revision ).

4

IS : 9506 - 1980

3.2.0 Outline of the Method — The sample is suitably decomposed to bring all sulphur compounds into the sulphate form. The sulphate is precipitated with barium chloride from an acidified EDTA solution. The precipitate is filtered off and dissolved in ammoniacal EDTA, the excess of which is titrated against magnesium chloride solution with eriochrome black T as indicator. There is no interference from iron, aluminium, fluoride or phosphate ions.

3.2.1 Reagents

3.2.1.1 Concentrated hydrochloric acid — See IS : 265-1976*.

3.2.1.2 Dilute hydrochloric acid — 0.05 M and 2 M.

3.2.1.3 EDTA solution — 0.05 M. Dissolve 18.6 g of disodium salt of EDTA in water and dilute to 1 000 ml with water.

3.2.1.4 Barium chloride solution — 5 percent ( m/v ).

3.2.1.5 Ammonium hydroxide — relative density 0.90.

3.2.1.6 Buffer solution — Dissolve 70.0 g of ammonium chloride in a mixture of 570 ml of ammonium hydroxide ( relative density 0.90 ) and 250 ml of water and dilute to 1 000 ml with water.

3.2.1.7 Standard magnesium chloride solution — 0.05 M. Dissolve 10.16 g of magnesium chloride ( MgCl2. 6H2O ) in water and dilute to 1 litre. Standardize with 0.05 M EDTA solution with eriochrome black T as indicator.

3.2.1.8 Indicator solution — Dissolve 0.40 g of eriochrome black T in a mixture of 30 ml of triethanolamine and 10 ml of absolute alcohol.

3.2.2 Procedure — Decompose 1 g of the ground material with 10 ml of concentrated hydrochloric acid and evaporate nearly to dryness. Redis-solve the residue in 100 ml of dilute hydrochloric acid ( 2 M ) .F i l t e r through filter paper ( Whatman No. 40 or equivalent ). Transfer residue to the paper and wash with hot water 10 times. Transfer the filtrate into a 250-ml calibration flask and dilute it to the mark with water. Take 25 ml aliquot of the solution in a 250-ml beaker and add to it 10 ml of EDTA solution. Boil gently for 2 minutes and then add 125 ml of dilute hydrochloric acid ( 0.05 M ). Allow to stand for a few minutes. Slowly add 50 ml of barium chloride solution. Allow to stand for 5 minutes only. Filter through filter paper ( Whatman No. 40 or equivalent ). Wash it with 25 ml of dilute hydrochloric acid ( 0.05 M ), then 50 ml of hot water till free from chloride. Transfer precipitate with filter paper into

*Specification for hydrochloric acid ( second revision ).

5

3.2 Indirect Method

IS : 9506 - 1980

original beaker. Add 20 ml of EDTA solution, 4 ml of ammonium hydroxide and dilute to about 150 ml with water. Heat for 15 minute. Allow to cool and add 5 ml of buffer solution. Titrate against magnesium chloride solution with eriochrome black T as indicator, keeping the beaker preferably on a white porcelain tile.

NOTE — Material under analysis has to be suitably treated to bring sulphur compounds to the form of sulphate. Organic material, for example coal, should be decomposed with Eschka mixture, sulphide and pyrite bearing material with bromine and concentrated nitric acid finally converted to chloride and taken up with 100 ml of dilute hydrochloric acid ( 2 M ).

3.2.3 Calculation Sulphate (as SO4), percent by

mass = × 96.06 × 100

where V1 = volume in ml of EDTA solution added, V2 = volume in ml of magnesium chloride solution required

for back titration, M1 = molarity of EDTA solution, M2 = molarity of magnesium chloride solution, and M = mass in g of sample taken for the test.

6

INTERNATIONAL SYSTEM OF UNITS ( SI UNITS ) Base Units

QUANTITY

Length Mass Time Electric current Thermodynamic

temperature Luminous intensity Amount of substance

Supplementary Units

QUANTITY

Plane angle Solid angle

Derived Units

QUANTITY

Force Energy Power Flux Flux density Frequency Electric conductance Electromotive force Pressure, stress

UNIT

metre kilogram second

ampere kelvin

candela mole

UNIT

radian steradian

UNIT

newton joule watt weber tesla hertz siemens volt pascal

SYMBOL

m

kg s A K

cd mol

SYMBOL

rad sr

SYMBOL

N

J W

Wb T

Hz

S V Pa

D E F I N I T I O N

1 N = 1 kg.m/s2

1 J = 1 N m 1 W = 1 J/s 1 Wb = 1 V.s 1 T = 1 Wb/m2

1 Hz = 1 c/s (s-1) 1 S = 1 A/V 1 V = 1 W/A 1 Pa = 1 N/m2

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