Percentage Purity of Sulphuric Acid

 

Process:

ð  Weigh 2 g of the sample accurately in weighing bottle.

ð  Transfer the same sample in a 500 ml. volumetric flask.

ð  Made the solution up to 500 ml. with distilled water.

ð  Pipette out 10 ml. from the same solution using volumetric pipette and transfer it into a conical flask.

ð  Add 2 – 3 drops of phenolphthalein indicator.

ð  Titrate it against 0.1(1/10)N NaOH (sodium hydroxide).

   

Chemical Reaction:

2NaOH_(aq) + H₂SO_{4 (aq)} à Na₂SO_{4 (aq)} + 2H₂O_(aq)

Calculation:

            1000 ml 1 NaOH   ≡  49 g H₂SO₄

1000 ml 0.1 N NaOH   ≡  4.9 g H₂SO₄

1 ml 1 N NaOH  ≡  0.0049 g H₂SO₄

 

% Purity =  Burette Reading (BR) X Eq.Wt.

                                            4

 % Purity =  (BR) X 49

                           4

 % Purity =  (BR) X 12.25

                     

Answer: % Purity of H₂SO₄ is (BR) X 12.25

Identification of Cotton Fibre (Physical Test)

 

Density Measurement for Fiber

 Equipment and Reagent:-

ð  10 ML graduated cylinder and either 100 ml graduated cylinder or six 20 ml beakers.

ð  Two liquids of known densities which are miscible in all proportions and, which will, when correctly mixed, give a range of densities from 1.0 to 1.60.

ð  Suggested liquids are

• Carbon tetrachloride (sp. gr. 1.60) and xylene (sp. gr. 0.87)
• Carbon tetrachloride (sp. gr. 1.60) and n-heptane (sp. gr. 1.10)
• Perchloroethylene (sp. gr. 1.63) and xylene (sp. gr. 0.87)

Manipulation:-

ð  Fiber density can be determined in two ways: by using density gradient tube or graduated series of liquids of known densities.

ð  Density Gradient Tube:-

·    It is prepared using 10 ml graduated cylinder, prepare the mixture of carbon tetrachloride and xylene respectively; 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 ml/ml; add carefully 10 ml carbon tetrachloride in to 100 ml of xylene.

·     Add above nine mixtures and pour 10 ml of xylene on top.

·    The mixtures should be added in such a way that one mixture will not penetrate more than depth of 12 ml into previous mixture. 

·     The cylinder will now have a column of liquid, the density of which varies continuously down its length from 1.6 at the bottom to 0.87 at the top.

·    Now, wet out the fibers in warm xylene, dry them, and cut them into very short lengths (1mm).

·     Place them on a sheet of paper and tease them apart so that no fiber is adhering to any other.

·      Then lay them on the surface of the liquid in the cylinder. With a stirring rod, shove the fibers under the surface of the liquid and allow them to seek their level of density.

·       After 10 – 15 minutes, read off the levels at which the fibers float and identify them by referring to the below table.

Table:- Densities of Fibers

Fiber	Density (g/cc)
Cotton	1.50
Viscose	1.52
Wool	1.32
Silk	1.33
Nylon 66	1.14
Nylon 6	1.14
Polyester	1.38

Microscopic Examination for Fiber Identification

  

•  For fiber analysis, microscope is one of the most powerful tools, to see the surface characteristics and cross-sectional shape of the fibers.

 Equipment:-

•  A microscope of good quality, with magnification from 100 to 450 diameters.
• Supplemental requirements are: number of regular glass microscope slides and cover glasses, a dozen or more small glass bottles fitted with medicine droppers, pair of fine pointed tweezers, dissecting needle, a micro-tome of cross-section block, razor blades, and a light source.

Manipulation:-

• The most important step in the microscopic examination is preparation of the slide.
• Fibers to be examined should first be degreased by washing in petroleum ether or carbon tetrachloride.
• After drying the fibers on a piece of blotting paper, they are transferred to the microscope slide.

ð  For longitudinal View:-

·     Cut the fibers into short lengths, not over 1/8”, and place them in a flask containing either water to which a little wetting agent has been added or ethyl alcohol.

·     Fibers are mounted on glass plate with mounting medium and covered with cover glass.

ð  For Cross sectional View:-

·     The simplest method of preparing cross sectional view is the cross section plate. This is a stainless steel plate, the size and shape of microscope slide with two rows of five holes each drilled in it.

·     One row has holes 1/32” in diameter, the other 1/64” in diameter.

·     The projecting fibers through the plate are cut off flush with the surface of the plate with a sharp razor blade.

·      Fibers are mounted on glass plate with mounting medium and covered with cover glass.

Table:- Microscopic View of Fibers

Fiber	Longitudinal View	Cross sectional View
Cotton	A flattened, collapsed, spirally twisted tube with a rough surface, and frequent convolution that change direction	Flat, elongated or bean shaped with lumen as a line or oval parallel to the larger direction
Viscose	Uniform diameter with striations running parallel to the fiber axis	Roughly circular or irregular in cross-section with separated or scalloped edges according to the process used
Wool	Irregular and roughly cylindrical, prominent scale margins or flattened plates	Oval to circular with variation in diameter. Medulla is concentric and variables in size
Silk	Flat irregular ribbons, twisted and with longitudinal striations	Very elongated triangles normally separated, with round corners
Nylon 66	Very regular, rod like	Circular
Nylon 6	Very regular, rod like	Circular
Polyester	Very regular, rod like	Circular

Reference: 

Textile Testing and Analysis by N A Vaishnav and H D Joshi, Popular Prakashan

Burning Test for Fiber Identification

• The oldest test used to identify the fibres is burning test.
• It consist of following observations:

(a)    Odour of the gaseous products of combustion (smoke)

(b)   Rate and character of burning

(c)    Action after removal of flame

(d)   Character of ash

Equipment:- source of flame

ð  The best sources are a Bunsen burner or an alcohol lamp.

ð  Cigarette lighter can also be used as a source.

ð  Match is a poorest source, as its burning odour.

Manipulation:-

ð  Fibre should be heavy yarn; length should be 1.5 to 2” by twisting.

ð  Twist of the fibre should be tight, so burning rate will be slow.

ð  The fibre sample should be slowly introduced to the flame from the side.

ð  If the fibre burns in the flame, remove it and note whether it continue to burn. (if it burns without contact with the flame is said to support combustion)

ð  If the fibre fails to support the combustion, quickly note the odour of the gaseous products of combustion.

ð  Do not move the fibre any more than is absolutely necessary as this will cause the smoke to be dispersed in the air.

ð  Note also whether the fibre continues to glow after the flame has been extinguished.

ð  Finally examine the ash from the standpoint of amount from colour and hardness.

ð  Table shows the burning characteristics of the fibre under the conditions stated above.

Reference: 

Textile Testing and Analysis by N A Vaishnav and H D Joshi, Popular Prakashan

Percentage Purity of NaOH (Sodium Hydroxide)

 

Process:

ð  Weigh 2 gm of the sample accurately in weighing bottle.

ð  Transferred the same sample in a 500 ml. volumetric flask.

ð  Made the solution up to 500 ml. with distilled water.

ð  Pipette out 10 ml. from the same solution using volumetric pipette and transferred into a conical flask.

ð  Add 2 – 3 drops of phenolphthalein indicator.

ð  Titrate it against 0.1(1/10)N HCl (Hydrochloric acid).

 Chemical Reaction:

NaOH_(aq) + HCl_(aq) à NaCl_(aq) + H₂O_(aq)

Calculation:

Answer: % Purity of NaOH is (BR) X 10

 

Percentage Purity of HCl (Hydrochloric acid)

 

Process:

ð  Weigh 2 gm of the sample accurately in weighing bottle.

ð  Transfer the same sample in a 500 ml. volumetric flask.

ð  Made the solution up to 500 ml. with distilled water.

ð  Pipette out 10 ml. from the same solution using volumetric pipette and transfer it into a conical flask.

ð  Add 2 – 3 drops of phenolphthalein indicator.

ð  Titrate it against 0.1(1/10)N NaOH (sodium hydroxide).

    

     Chemical Reaction:

HCl_(aq) + NaOH_(aq) à NaCl_(aq) + H₂O_(aq)

Calculation:

Answer: % Purity of HCl is (BR) X 9.12

Identification of Dyestuffs

(A)                       Preliminary Tests

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Appearance of dye Powder	Amorphous	Direct, Acid, Basic, Sulphur, Mordant, Vat, Naphthols, Fast bases, Salts, Rapid fast, Indigosol etc.
		Crystalline	Some Basic dyes, Disperse dye
		Flakes like	Aniline salts
2.	Colour of Powder	Bright, Shining	Basic
		Bright	Direct, Acid, Basic, Vat, Mordant etc.
		Dull	Sulphur
		Light colour	Indigosols, Naphthols, Fast salts, Some Fast bases, Rapid fast, Rapidogen etc.
3.	Weight of Powder	Light	Basic, Direct, Vat, Acid etc.
		Heavy	Pigments
4.	Smell of Powder	Phenolic	Naphthols
		Aromatic	Fast bases, Salts
		Sweet Smell like chloroform	Indigosols

(B)                        Solubility Tests

Sr. No.	TESTS	OBSERVATION		INFERENCE
1.	Dye Powder + Water (Heat the Solution) Original Solution	A	Dissolves in warm but precipitated at boiling	Fast salts
		B	Dissolves very freely giving a faint coloured solution	Indigosols, Aniline salt
		C	Dissolves very freely giving a deep coloured solution (Transperent)	Direct, Basic, Reactive, Acid, Acid mordant etc.
		D	Insoluble particles in suspension condition	Naphthol, Vat, Sulphur, Fast bases, Pigments
		E	Insoluble particles in disperse condition	Disperse

Preliminary Tests For A

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution  + Naphthol Solution	Deep Coloured Solution	Fast salts

Preliminary Tests For B

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution  + NaNO2 + dil. HCl or H2SO4 & Heat	Deep Coloured Precipitates	Indigosol
		No ppts.	Pre –Aniline Salt

Preliminary Tests For C

Sr. No.	TESTS	OBSERVATION		INFERENCE
1.	Original Solution  + Tannin Reagent & Heat	Precipitates are obtained in few minutes		Basic Dye
		No ppts.		Direct, Acid, Acid mordant
2.	Original Solution + Wool + Tanned Cotton + Acetic Acid (2 – 3 drops) & Heat	I	Both Cotton & Wool dyed in full shade. Not fast to rubbing	Basic Dye
		II	Cotton dyed deeper then wool & fast to rubbing	Direct Dye, Reactive dye
		III	Wool is dyed & Cotton stained, it is stripped in hot dil. NH3	Acid, Acid mordant

Preliminary Tests For D

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original powder + dil. HCl + NaNO2. Drop by drop	A clear solution is obtained after few minutes which give coloured ppts. With naphthol solution	Base
		No ppts.	Naphthol, Vat, Sulphur etc.
2.	Powder + NaOH solution + Water & Heat	Dissolve freely giving clear solution	Naphthol, Rapidogen
		Insoluble	Sulphur, Vat
3.	Original Solution + dil. Acetic acid or Formic acid & Heat	Coloures ppts.	Rapidogen
		ppts. as Original substance	Naphthol
4.	Powder + Na2S & Heat	Dissolve freely with a change in colour	Sulphur
		Do not dissolves	Vat
5.	Powder + NaOH + Na2S2O4 & Heat	Dissolve with a change in colour	Vat

(C)                       Confirmative Tests

Confirmative Tests for Fast Salt

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution + Naphtholated yarn	Deep colour Yarn dyed in full shade	Fast Salt
2.	Fastness test	Not fast to rubbing	Fast salt

Confirmative Tests for Indigosols

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution + NaNO2 + Cotton, Warm squeeze & put in hot dil H2SO4 Solution	Cotton gets dyed, in full shade	Indigosol
2.	Dyed yarn + NaOH + Hydro, & Heat	Colour is reduced & restored in air or persulphite	Indigosol
3.	Fastness test	Fast to all	Indigosol

Confirmative Tests for Aniline Salt

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution + dil H2SO4 + Cotton + K2Cr2O7 (drop) & Heat	Cotton is dyed, from brown to black colour	Aniline salt
2.	Bleaching test	Turns brown or diminished	Aniline salt
3.	Fastness test to rubbing	Not fast to rubbing	Aniline salt

Confirmative Tests for Basic Dye

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Dyed wool + white Cotton + white Wool + Soap solution & heat	White Wool is dyed deeper than white Cotton	Basic dye
2.	Dyed wool + 10 % Sodium hydrosulphite solution	Dye is not stripped and no effect on original shade	Basic dye

                   

Confirmative Tests for Direct Dye

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original solution + Cotton + 2 – 3 drops Soda ash + NaCl Boil	Cotton is dyed in deep shade	Direct dye
2.	Dyed cotton + NaOCl solution	Colour is discharge within 5 – 7 minutes	Direct dye
3.	Dyed cotton + white Cotton + Soap solution, Boil	White cotton stained	Direct dye

Confirmative Tests for Reactive Dye

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution + Cotton & after dyeing add Cotton & H2SO4	Dye stained untreated cotton and partially stripped from dyed cotton	Reactive dye
2.	Above dyed cotton + Pyridine or Chloroform , Warm	No effect	Reactive dye

Confirmative Tests for Acid Dye

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution + Wool + CH3COOH + Cotton & Heat	Wool dyed deeper than Cotton or Cotton is not dyed	Acid dye
2.	Dyed wool + Strong hydrosulphite solution	Dye stripped from the dyed fibre	Acid dye
3.	Dyed wool + K2Cr2O7 + water & Heat for 5 minutes (Treated wool) + Soap solution, Boil & untreated dyed wool + soap solution & boil separately	Colour is stripped from both dyed samples	Acid dye

Confirmative Tests for Acid Mordant

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution + Wool + Cotton & Heat	Wool dyed deeper than Cotton or Cotton is not dyed	Acid mordant
2.	Dyed wool + drop of  K2Cr2O7 ­+ Water & Heat	Colour become deeper or changed on tone	Acid mordant
3.	Dyed wool (untreated with K2Cr2O7) + Soap solution & Heat	Colour stripped	Acid mordant

Confirmative Tests for Fast Base

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original Solution* + Naphtholated yarn	Yarn is dyed in deep full colour	Fast Base
2.	Fastness to rubbing	Not fast to rubbing	Fast Base
3.	Dyed cotton + NaOCl solution	No change in colour of the dyed cotton	Fast Base
4.	Dyed cotton + Rongolite – C + CH3COOH , Boil	Original colour of the dyed cotton is changed	Fast Base

·         Original solution made by HCl + NaNO₂ +Sodium acetate

Confirmative Tests for Rapidogen

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original solution + Yarn + Hot  Acetic acid	Yarns get dyed	Rapidogen

Confirmative Tests for Naphthol

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Original solution + Fast salt	Deep coloured ppts.	Naphthol
2.	Original Solution + Yarn & put it in fast salt solution	Yarn gets dyed in full shade	Naphthol

Confirmative Tests for Sulphur Dye

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Powder + SnCl2 + Conc. HCl & Heat	Lead acetate paper turns brown to black with silvery effect	Sulphur dye
2.	Fastness to bleaching	Loose to bleach	Sulphur dye
3.	Powder + Na2S + cotton & Heat	Cotton dyed with full deep colour	Sulphur dye

Confirmative Tests for Vat Dye

Sr. No.	TESTS	OBSERVATION	INFERENCE
1.	Dyed cotton + Soap solution  Boil for 2 minutes	Colour is not remove	Vat dye
2.	Dyed cotton + NaOCl	Fast to bleach	Vat dye
3.	Dyed fibre + Formic acid (85 %), Boil	Colour is not remove	Vat dye
4.	Dyed fibre + Na2S2O4 solution	No change in colour	Vat dye