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T.V.Rajale

T.Y.B.Sc. Chemistry

Sem. –V

Course No:- CH-368

Subject: Inorganic Chemistry Practical.

Experiment :- 1 to 6

Inorganic Qualitative Analysis: (Six binary Mixtures containing common anions)

(Excluding phosphates and borates)

Experiment :-7 to 8

2. Ore Analysis: (Any Two)

Heamatite ore - Estimation of Iron volumetrically

Pyrolusite ore- Estimation of Manganese volumetrically

Dolamite ore - Estimation of Calcium volumetrically

Experiment :-9 to 10

3. Alloy Analysis : (Any Two)

i) Estimation of Zinc from Brass Alloy by EDTA method.

ii) Estimation of Tin gravimetrically as SnO2 from solder alloy.

iii) Estimation of Copper iodometrically from nichrome alloy.

Minerals :-Naturally occurring inorganic solid definite chemical composition ordered internal structure

Rocks- A rock is made up of two or more minerals. You need minerals to make rocks, but you don't need

rocks to make minerals. All rocks are made of minerals.

Ore:- Naturally occurring source of mineral from which metals are extracted economically. Processed

mineral (Usually heterogeneous)

Alloy:- A homogeneous mixture of a metal with other types of elements( Generally metals have zero

oxidation state)

T.V.Rajale

INORGANIC QUALITATIVE ANALYSIS

The given plot of analytic procedure will help to identify Acid and Basic radicals in stepwise manner and the

chance of error can be minimized.

Physical observations:

A) State

B) Colour

Chemical observations:

A) Dry test basic radicals(preliminary tests)

B) Dry test acidic radicals(preliminary tests)

C) Wet test acidic radicals (Confirmatory tests)

D) Wet test basic radicals (Confirmatory tests)

Preliminary examination of a salt often furnishes important information, which simplifies further course of

analysis. Although these tests are not conclusive but sometimes they give quite important clues for the

presence of certain anions or cations. These tests can be performed within 10-15 minutes. These involve

noting the general appearance and physical properties, such as colour, smell, solubility etc. of the salt. These

are named as dry tests.

Precautions:-

(a) Firstly read Test and observation completelythen and then only perform test (b)Before using any reagent or a chemical, read the label on the bottle carefully. Never use unlabeled

Reagent.

(c) Do not mix chemicals and reagents unnecessarily

(d) Be careful in smelling chemicals or vapours. Always fan( by hand) the vapours gently towards your nose

(e) Always pour acid into water for dilution. Never add water to acid.

(f) Be careful while heating the test tube. The test tube should never point towards yourself or towardsyour

neighbours while heating or adding a reagent.

(g) Always use the reagents in minimum quantity. Use of reagents in excess, not only leads to wastage of

Chemicals but also causes damage to the environment.

T.V.Rajale

Preliminary Test

Test Observation Inference

1. Nature Crystalline ( water soluble) SO42-

, NO3-,Cl

- , Br

- , I

- of soluble salts or CO3

2- of

alkali salts present/may be present.

Amorphous ( water insoluble) CO3-2,

BO3-3

, PO4-3

of heavy metal salts present/may

be present.

2. Colour Pink Co2+

, Mn2+

salts present.

Green/Bluish green Cu2+

, Fe2+

, Cr3+

, Ni2+

salts present

Blue Hydrated Cu2+

salt present

Black CuO, CuS, PbS, NiS, CoS, MnO2 salt present

Yellow

PbO, SnS, PbI2, CdS, As2S3, CrO42-

salts present.

Orange or Red Dichromate and Sb2S3 salts present

Coloured Coloured radical present

White/Colourless Coloured salts are absent,Salts of

Na+,K

+,NH4

+and alkaline earth metals, Al, Zn, Ca,

Sr, Ba, Mg, salts may be present .


Dry tests for Basic radicals:-

1.Heating in dry

test tube:-Take a

pinch of mixture in

dry test tube and heat

it strongly. Observe

the changes taking

place (test tube hold

almost horizontal on

the burner flame.)

a) Decrepitating (crackling sound is

produced due to the breaking of the crystals

and particles flying off) (no decrepitating )

Salts like NaCl, KCl, KNO3, KI,

Pb(NO3)2 etc. present/may be present.

a) b) Substance fuses( just melt) or ( shrinks)/

b) (no particular observation)

Salts of Na+, K

+, NH4

+ or some salts

of Ca2+

, Ba2+

, Sr2+

, Mg2+

or hydrated

salts etc.

c) Sublimation (Condenses on cooler part

of test tube.)

i) Greyish or Black

ii) White

iii) Yellow

/(no particular observation)

I-, As

3+, Sb

3+ salts etc.

NH4+, As

3+ Sb

3+ salts etc

S2-

salts etc

d) Change in colour of residue

blue to white Cu2+

green to yellow Ni2+

yellow (when hot) to white (when cold) Zn2+

, Sb3+

colourless to brown or black on heating Cd+2

white residue, glows on heating Ca+2

, Ba+2

,Sr+2

, Mg+2

, Al+3

,K+

Black (when hot) to Rusty red or brown

(when cold)

Fe2O3

Orange or Red (when hot) to yellow (when

cold)

Bi+3

, Pb+2

Black (when hot) to Black (when cold) MnO2,CuO,CoO,NiO,FeS ,CoS

Violet (when hot) to Blue (when cold) Co+2

Yellow (when hot) to yellow (when cold) Pb+2

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e) Gas evolved

Colourless gas turns lime water milky CO3-2

or SO4-2

Characteristic vinegar like smell CH3COO-

Greenish yellow gas with suffocating odour,

smell of chloride, bleaches moist litmus

paper

Cl-

Red brown vapours turn starch paper yellow Br-

Violet vapours turn starch paper blue I-

Dark brown or reddish fumes, acidic in

reaction

NO3-

Colourless gas with smell of burnt sulphur

and turns K2Cr2O7 paper green

Sulphites salts

Colourless gas with smell of rotten eggs,

blackens lead acetate paper

Sulphide salts

Colourless gas turns blue litmus red and

produces fumes over glass rod dipped in

ammonia solution

Cl-

Smell of ammonia, turns red litmus blue NH4+

2. Charcoal cavity

test:-Mix.0.05gm of

mixture with double

quantity of Na2CO3

and fill in cavity of

charcoal. Add 2-3

drops of water. Heat

cavity with blow pipe

in a reducing

flame(yellow).

a) fusion and sinking in the cavity Na+, K

+, NH4

+

b) Decrepitationi.e,crackling sound and

flying about of particles.

NaCl, KCl, KNO3, KI, Pb(NO3)2

c) Deflagration with the sparks and residue

turns green

NO3- salts

d) Fumes and incrustation (the fumes

evolved get deposited on the cooler sides

round about the cavity)

NH4+, S

-2, I

-1

e) Metal beads formed

i) Rusty red Fe2O3

ii) Yellow incrustation with brittle bead Bi+3

, Pb+2

iii) Malleable bead that marks the paper

black

Pb+2

iv) Yellow malleable bead that does not

mark paper black

Sn+2

v) Red flakes Cu+2

vi) Grey metallic particles without

incrustation.

Fe2+

, Co2+

, Ni2+

vii) White infusible mass Mg2+,

Ba2+,

Sr2+

,Ca2+

,Al3+

,Zn2+

3. Co(NO3)2 test:-

This test is performed

only when residue in

charcoal test remains

white.Add one drop

of 5%Co(NO3)2

solution and heat

residue in an

a) Blue mass Al3+,

PO43-

salts.

b) green mass Zn2+

salts etc.

c) pale pink or indistinct mass Mg2+,

Ba2+,

Sr2+

,Ca2+

salts etc.

T.V.Rajale


Dry tests for acidic radical(Can be identified by volatile products except SO4-2

):-

1. Action of dilute acid (HCl or

H2SO4):-

Little mixture in a test tube +

3-4 ml dil. H2SO4

Evaluation of gases

a) Colourless ,odourless gas evolved with

brisk effervescence turning freshly

prepared lime water milky.

CO3-2

, SO4-2

may be

present.

b) Colourless gas with effervescence and

with suffocating odour, turning

acidified potassium dichoromate paper

green.

SO3- -

c) Colourless gas with little

effervescence. Smell of rotten eggs,

turning moist lead acetate paper black

brown or shining.

S- -

d) brown fume with little effervescence. NO2-

2. Mixturewith double the

quantity of MnO2 and 4-5

drops of conc. H2SO4. Warm it

gently

a) Greenish yellow gas bleaches moisten

litmus paper

Cl-

b) Reddish brown gas with characteristics

odour turns starch paper yellow

Br-

c) Voiletvapour with characteristics odour

turns starch paper bluish back. Forms a

I-

oxidizing flame

(blue).

4.Flame test:-

Mixture 0.05 g of the

mixture with 2-3 drop

of conc. HCl on clean

watch glass and

prepare a paste of it.

Take it on a match

stick head

(Nick chrome) and

heat in an oxidizing

flame.

Observe the color of

the flame with naked

eye and then through

cobalt glass.

a) crimson K+

b) Bluish green Ba2+

c) Light green Ca2+

d) Purple Sr2+

e) Blue Cu2+

f) White Bi3+,

pb2+,

Sn2+,

As3+,

sb3+,

Cd2+

etc

5.NaOH test

(Sodalime Test):-

Mixture +NaOH

solution and boil

a) Evolution of ammonia gas but

turmeric paper remain unchanged.

NH4+

may be present

b) Smell of garlic salt

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black crystalline deposit on cooler parts

of the test tube

3. Mixture +Cu filling + Con.

H2SO4+ warm

Dark brown fumes of evolved

NO3-

4. 4. Chromyl Chloride Test:-

the mixture initially with

double the quantity of solid

on a piece of paper.

Take this mixture in a test tube

add 3-4 drops of conc.

and heat it. Collect the gas

evolved in another test tube

containing a few drops of

dilute NaOH solution

Yellow coloured solution. Add 2-3 drops of

solution to it. Yellow precipitate

of PbCr

Cl-

Wet Tests andConfirmetory test for Anions or acidic radicals:-

(i) Wet test for anions are done first as it helps us to confirm anions. It also helps us in preparation of

original solution for cations, because some of the anions interfere in the separation of groups and

analysis.

(ii) For each test ,4-5 drops of extact should be used in a test tube.

(iii) and are detected and confirmed in dry test test.

A) If mixture is water soluble then use Water Extractfor detection of anions.

B) If mixture is water insoluble then use sodium carbonate extract (S.C.E)and neutral sodium carbonate

extract(N.E)for detection of anions.

A) Preparation of Water Extract (W.E.): Take about 0.05 g of the mixture in a 25 ml beaker containing 10ml

of distilled water. Boil it strongly and Filter. Fitrate is W.E. Perform the wet tests for anions like ,

and analysis the VIth group for , and

from this W. E.

B) Preparation of sodium carbonate extract (S.C.E)and neutral sodium carbonate extract(N.E) :-

1. Add about 2gm of pure sodium carbonate to about 1gm of mixture.

2. Add about 25ml distilled water and boil for 10 min. in a Conical flask.

3. Filter of reject the residue. Add 20-25 ml distilled water to the filtrate(S.C.E) .keep 10-15ml extract for

detection of S- -

,NO2- -

,NO3- -

.

4. Neutralize the remaining filtrate by adding dil.HNO3and make it little acidic , then add NH4OH till the

extract become basic to litmus

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5. Boil the solution to completely evolve NH3and CO2,and cool. Use this neutral solution(N.E) for

detection of halide.


1) 2-3 drops of W.E/N.E +

3-4 drops of 5% BaCl2 or

Ba(NO3)2 solution

a) Yellow precipitate soluble in dilute HCl CrO4-2

or Cr2O7-2( If

mixture or W.E. is yellow

CrO4-2

present and if it is

orange Cr2O7-2present).

b) White precipitate insoluble in dilute HCl SO42-

2) 2.3 drops of W.E/ N.E+

dilute HNO3 till acidic +

3-4 drops of 5%

AgNO3solution

a) White or yellow ppt. insoluble in dil. HNO3

i) White precipitate soluble in excess NH4OH

ii) Yellowish White precipitate partially

soluble in excess NH4OH

iii) Yellow precipitate insoluble in NH4OH

Cl- ,

Br-, I

- present.

Cl-

Br-

I-

b) Yellow ppt. soluble in dil. HNO3 PO3-

4 present

c) Brick Red soluble in dilute HNO3 CrO2-

4 or Cr2O2-

7 present

d) White precipitate soluble in dilute HNO3

completely

SO2-

4 present

e) White precipitate soluble in dilute HNO3 with

effervescences of CO2

CO3- -

f) Black or Blackish Brown precipitate S2-

present


3) 2-3 drops of S.C.E/W.E +

dilute H2SO4 till acidic. Add 1-2

drops of freshly prepared FeSO4

solution from the side of the test

tube.

Brown ring or coloration.

NO-2 present

4) 2-3 drops of S.C.E/W.E +

Conc H2SO4 till acidic. Mix

thoroughly and cool the solution. .

Add 1-2 drops of freshly prepared

FeSO4 solution from the side of

the test tube.

Brown ring forms at the junction.

NO3- present

Confirmatory Tests For Anions.

1. Acidify 2-3 drops of W.E.

or N.S with Conc.H2SO4

or HNO3 + 1 ml of CHCl3

+ 1 ml of saturated

chlorine water. Shake

well.

a) Violet colored layer

forms.

I-

Confirmed.

b) Brown Layer forms. Br- confirmed.

2. Add little solid K2Cr2O7 to

the mixture + concentrated

Yellow ppt of lead chromate is

formed.

CI-

Confirmed.

T.V.Rajale

H2SO4 warm gently. Pass

the evolved vapours into

lead acetate solution.

3. Water solution +dil.

CH3COOH till acidic +

lead acetate solution.

White ppt insoluble in dilute

HNO3.

SO42-

4. Little mixture in a test

tube + 3-4 ml dil. H2SO4

Colourless ,odourless gas evolved

with brisk effervescence turning

freshly prepared lime water

milky.

CO3- -

2-3 drops of S.C.E + dilute

H2SO4 till acidic. Mix thoroughly

and cool the solution. . Add 1-2

drops of freshly prepared FeSO4

solution from the side of the test

tube.+ 3-4 drops conc. H2SO4

Brown ring forms at the junction. NO3-

WET TEST FOR BASIC RADICALS

Instructions:

Group Seperation :(Salt Solution + Group Reagent → Precipitate) → Filtered → Residue

Group Analysis : (Residue + Reagents → Precipitate of Specific Colour) i.e. Cation is Confirmed

A) Preparation of solution:- In qualitative analysis when we analyses basic radicals by wet test we have to prepare the solution of the

mixture. When a mixture gives transparent solution with the solvent then it is called Original Solution.

Many solvents are used to prepare the solution. Taking 0.1 gm. of mixture put the solvent in the following

order:

(1) Distilled Water :- In the cold and hot form.

(2) Dilute HCl: - In the cold and hot form.

(3) Concentrated HCl :- In the cold and hot form.

(4) Aqua-regia:- conc. HCl and conc. HNO3 in the ratio 3:1 is tried

(5) Mixture partly soluble in water:-If mixture is partly soluble in water then filter it. The filtrate is used for

group I to VI. The residue is dissolved in acid and is used for analysis of group II to V

NOTE

1) Use very small quantity of solution.

2) Once the particular group detected then remove that group completely from the whole solution.

T.V.Rajale

Filter it.Use the filtrate for further group detection and use precipitate for the identification of radical in

that group. Firstly do group analysis of detected group

3) For group II extremely dilute solution is required for precipitation and For group IV extremely

concentrate solution is required for precipitation

Group Separation


1) O.S+ dil. HCl Ppt. obtained.

No ppt.

Gr.I present

AgCl-White

Hg2Cl2- White

PbCl2- White

Gr.I radicals absent

2) O.S/filtrate + dil. HCl +H2S pass

Ppt. obtained.

No ppt.

Gr.II present

CuS-Black

PbS-Black

Bi2S3-Brown

SnS-Brown

CdS-Yellow

Sb2S3-Orange

Gr.II radicals absent

3) 3) O.S/filtrate + NH4Cl solid (excess)+NH4OH(till

alkaline)

Ppt. obtained.

No ppt.

Gr.IIIA present

Al(OH)3-White Gelatinous

Cr(OH)3-Green

Fe(OH)3-Reddish

MnOH)3-Brown

Gr.IIIA radicals absent

4)

4) O.S/filtrate O.S. + NH4Cl(s) (excess)+ NH4OH

(till alkaline )+ H2S pass

Ppt. obtained.

No ppt.

Gr.III B present

ZnS-White

MnS-Green

NiS-Black

CoS-Black

Gr.III B radicals absent


(till alkaline )+ (NH4)2CO3

Ppt. obtained.

No ppt.

Gr.IV present

BaCO3-White

CaCO3-White

SrCO3-White

Gr.IV radicals absent


(till alkaline )+ Na2H(PO4)

Ppt. obtained.

No ppt.

Gr.V present

MgNH4PO4- White

Gr.V radicals absent

7) If all group absent then - Gr.VI:- NH4+,K

+ present

T.V.Rajale

Group Analysis

Analysis of group I:-

Transfer the ppt. in a beaker + 5 ml water and boil well, then filter when hot

Residue Filtrate

Residue + conc. NaOH warm and filter It may contain PbCl2 as soluble in water

Residue Filtrate i) Filtrate + KI solution→Yellow ppt.(in cold)

ii) Filtrate + K2CrO4→Yellow ppt.

iii) Filtrate + dil. H2SO4→White ppt.

Pb+2

present and confirmed

Residue + aqua-regia and

boil + SnCl2→Black ppt.

Hg+ present and

confirmed

Acidify the filtrate with

dil. HNO3

If white ppt is formed

Ag+ present

Filtrate + KI

solution→yellow ppt.

Ag+ confirmed

Analysis of Group II

Separation of IIA & IIB:-Black ppt+yellow(NH4)2S+NaOH boil & filter.

Residue Filtrate

Wash the ppt with 2% NH4NO3 solution

&discard the washings.

Use this ppt for analysis of IIA.

Cu2+

,Pb2+

,Bi3+

,Cd2+

Acidify with dilute HNO3 & heat gently. If

yellow or orange ppt. then Group IIB present

Sb2+

,Sn2+

T.V.Rajale

Analysis of Group II A (Copper group)

Dissolve the precipitate in 1cm3of 2N HNO3 and boil it.Add 1cm

3 of 2N H2SO4 to 2-3 drops of this solution. If

white precipitate forms, then add 2N H2SO4 to the whole solution drop wise,till the precipitation is complete,

separate the precipitate by filtration.

Residue Filtrate

Whiteppt of PbSO4 Treat

it with 0.1g of solid

CH3COONH4, 1ml of

CH3COOH&1cm3 of

H2O.boil strongly and

then filter. Acidify the

filtrate with 2N HNO3. 2

It is made alkaline with 4N NH4OH solution, boiled and Filter it.

Residue Filtrate

White ppt of Bi(OH)3. It

is dissolved in 2N HCl.

2 drops of solution are

poured in 10 ml of

It is boiled with 0.5-1ml of Na2S2O4(sodium

dithionate) solution and centrifuged.

Residue Fitrate

T.V.Rajale

drops of this solution+2-

3drops of 5%

K2CrO4→yellow ppt of

PbCrO4.

Pb2+

present

C.T.

i) Filtrate + KI

solution→Yellow ppt.(in

cold)

ii) Filtrate +

K2CrO4→Yellow ppt.

iii) Filtrate + dil.

H2SO4→White ppt.

H2O→white ppt or

turbidity of BiOCl.

Bi3+

present

C.T.

(a) 2drops of soln +2N

HNO3 till acidic+2 drops

of 10% Thiourea soln.

shake well→yellow ppt.

(b) 2drops of soln +3-4

drops of

Na2SnO2→yellow ppt.

Metallic Cu. Dissolve it in

1ml conc. HNO3 by boiling

and neutralize it with 2N

NH4OH.2 drops of soln are

acidified with CH3COOH+3

drops of 5%

K4Fe(CN)6soln-reddish

brown ppt Cu2Fe(CN)6

Cu2+

present

C.T.

(a) 2 drops of solution + 2N

NH4OH till

alkaline→bluecolour + one

drop of it on 5% alpha

benzoin oxime regent

paper→green color

(b) A drop of solution on

tile + 2-3 drops of 1% Zn

acetate + drops of 5%

NH4HgSCN→violet color

Acidify it with 2N

HCl. Add 4-5ml of

H2O to dilute it.2 drops

of soln,heat and pass

H2S→ yellow ppt of

CdS.

Cd2+

present

C.T.

(a) 2 drops of

soln+2drops of H2O+5

drops of 0.25%

Ferrous dipyridyl

iodide reagent→ red

ppt.

(b) 2 drops of

solution+ a drop of

freshly prepared 0.1%

Dinitro p-

diphenylcarbazide

reagent→ violet or

pink colour

Analysis of Group IIB (Tin group )

Ppt. + Conc.HCl + double amount of water and boil for five minute and pass H2S.Filter it

Residue Filtrate

Orange ppt. of Sb2S3. Disslove it in 2N HCl. Boil off

H2S.Two drops of this solution are poured in 10ml of

water→ white ppt or turbidity of SbOCl

Sb2+

present

C.T

a) 2 drops + Zn dust ( 0.02gm) warm→black ppt.

b) Solution + KI+ pyridine→coloured solution

Boil off H2S; add Zn + dilHCl→Sn ppt.

Sn2+

present

Dissolve it in conc. HCl

C.T.

a) Soltuion + HgCl2→ white ppt. of Hg2Cl2 is

formed

b) Solution + dil. I2 Solution→ I2decolorised

Analysis of Group IIIA (Iron Group):

T.V.Rajale

Precipitate is washed with 2 ml of H2O, filter and washing is rejected. Washed ppt is boiled with 1 ml of 2N

NaOH solution. 1 ml of H2O and 3-4 drops of 20 volume H2O2 and filter.

Residue Filtrate

Brown ppt of (FeOH)3, Dissolve it. In 2N HCl

and dilute with 1ml of H2O2.

Divide the soln into two parts

Frist Part(for Fe3+)

3 drops of soln +3 drops of 5% KSCN sol

n

blood red soln or ppt of Fe(SCN)3.

Fe3+

present

C.T:

(a) 2 drops of soln +2-3 drops of

5%K4Fe(CN)6soln→ blue colour or ppt.

(b) 2 drops of soln+ 2 drops of 2N HCl + 2

drops of 2% cupferron reagent→ reddish

brown ppt.

Second parts (for Mn2+

)

2 drops of soln + 3 drops of 2N HNO3 + 0.002g

(pinch) of NaBiO3 (sodium bismuthate)→

pink or violet colour of HMnH4.

Mn2+

present.

C.T

(a) 2 drops of soln + 0.001 g of Na2S2O8 + 2-3

drops of 2N H2SO4 + adrop of 0.1N

AgNO3soln boil → reddish violet or purple

colour.

(b) 2-3 drops of soln + 0.002g PbO2 + 5-6 drop

of conc. HNO3→ boil strongly and allow it to

settle→ violet colour.

Divide into two parts

Frist part (for Al3+)

2 drops of soln + 2N HCl till acidic. Make it alkaline with 4N

NH4OH → white gelatinous ppt of Al(OH)3.→Al3+

present

C.T

(a) 2 drops of soln + 2-3 drops of conc. HCl+ 2-3 drops of

0.1% Aluminon reagent → shake well + 5 ml of alkaline

(NH4)2CO3soln (NH4OH : (NH4)2 CO3=14) red colour.

(b) 2 drops of soln + 2N HCl till slightly acidic + 5 drops of

2M CH3COONH4soln + 5 drops of 10% solochrome cyanine

reagent → centrifuge→ after sometime, upper layer

turns intents purple.

Second part(for Cr3+

)

3 drops of soln + 5 drops of 2N CH3COOH + 4 drops of 10%

Pb (CH3COO)2soln→ yellow ppt of PbCrO4.→

Cr3+

present

C.T

(a) 2drops of soln + 4N H2SO4 till acidic, cool + adrop of 20

volume H2O2 + 0.5 ml of 1% Ether-butanol mixture. Shake

well → blue organic layer.

Analysis of gorouplll B (Zinc group ):- Ppt. of III B with 15ml of dil.HCl and allow to stand for five minutes and filter.

Residue Fitrate

Ppt. + 2 ml aqua regia ( 3:1 conc. HCl: conc.

HNO3)+ evaporate slowly nearly to dryness then

cool extract with 2 ml water and divide in two

Filtrate is boil to expel H2S gas. Filtrate +NaOH

(excess).Filter

Residue Filtrate

T.V.Rajale

parts

Part I :- for Ni+2 3-4 drops of solution + 2N NH4OH till alkaline+ 3 drops of 1% DMG ( excess)→Scarlet red/rosy red ppt. Ni

+2is present and confirmed.

Part II :- for Co+2 a) 4-5 drops of solution + solid NH4Cl + NH3 till

alkaline + K3[Fe(CN)6] →reddish brown ppt

or solution b) 2 drops of solution on watch glass + one

crystal of Na2S2O3→blue colour around the

crystal Co

+2 is present and confirmed

White residue turning

brown due to atmosphere

oxidation.

Disslove the ppt. in conc.

HNO3 + pinch of PbO2 or

NaBiO3→pink or violet

colour

Mn+2

is present and

confirmed.

a) Acidify the filtrate with

acetic acid and pass H2S

gas.→ White ppt.

b) Acidify the filtrate with

acetic acid + few drops

K4[Fe(CN)6] + few drops of

diphenyl amine in

H3CCOOH→ Green ppt.

c) Acidify the filtrate with

dil.HNO3+ few drops

Co(NO3)2 and heat to

dryness→ Green mass

Zn+2

is present and

confirmed.

Analysis of group IV(Barium group ):-

Dissolve the precipitate in hot 2 ml of 2N CH3COOH. Test 2-3 drops of the solution with 0.5 ml of freshly

prepared saturated K2CrO4 solution. If yellow precipitate forms, then add 2 ml of K2CrO4 solution to the whole

solution and filter.

Residue Filtrate

T.V.Rajale

Analysis of Group V(Magnesiumgroup ):-

Dissolve the ppt. in dilHCl/Dil H2SO4

C.T for Mg+2

a) 2 drops of solution + 2 drops 0.1% Titan Yellow solution + 4 drops dilNaOH → red ppt

b) 2 drops of solution + Hypoiodite reagent ( NaOH + equal amount of KI + iodine solution till the

solution becomes just yellow)→reddish brown ppt

Analysis of Group VI:-

Use water solution or original water extract

Part I Part II

2-3 drops of W.E. + 5-6 drops of NaOH solution, boil

it and cover the mouth of test tube with moist turmeric

paper→smell of NH3and Turmeric paper turns

brown/red→ NH4+ present

Solution + Nessler’s reagent. .:=(Two drops of HgCl2 +

KI till scarlet red ppt. is formed and dissolved then add

equal amount of NaOH)→ Brown ppt is

formed→NH4+ confirmed

If is present, take 3 drops of W.E. + 5-6

drops of NaOH solution boil it to remove .

Then acidify it with acetic acid and add 3-4

drops of 5% sodium cobaltinitrite

solution. Shake well and allow it to stand for a

few seconds.→ Yellow precipitate of

→K+ present

Water solution + perchloric acid → white ppt. of

KClO4→K+ confirmed

Cation NaOH(aq) NH3(aq)

Little Excess Little Excess

Al+3

White ppt Ppt. dissolve to form

colorless solution

White ppt Ppt. remain insoluble

Yellow ppt of BaCrO4.

Dissolve the ppt in 2N

HCl. 2 drops of soln +

3-4 drops of 2N H2SO4

– white ppt of BaSO4.

Ba2+

present.

C.T.

(a) Obtained solution +

(NH4)2C2O4→ white

ppt.

(b) 2 drops of soln + 3

drops of freshly

prepared 10% sodium

rhodizoate reagent –

bright red colour.

Add 2N NH4OH till the solution becomes alkaline. Test 2-3 drops of the solution

with 0.5 ml of freshly prepared saturated (NH4)2C2O4 solution. If white

precipitate forms, then treat the whole solution with (NH4)2SO4, warm and filter.

Residue Filtrate

White ppt of SrSO4. Boil the ppt with 4N

HCl. filter it. Take 2-3 drops of filtrate +

4 drops of NH4OH + 0.5 ml of saturated

(NH4)2C2O4 solution – white ppt of

SrC2O4.

Sr2+

present

C.T.

(a) 2 drops of soln + 5 drops of 5%

K2CrO4soln + 2N NH4 OH soln till alkaline

– yellow coloured precipitate.

(b) 2 drops of soln on a tile + 3 drops of

freshly prepared 10% sodium rhodizoate

reagent – brownish red colour.

2-3 drops of soln + 3-4 drops of

saturated (NH4)2C2O4soln – white

ppt of CaC2O4.

Ca2+

present

C.T.

2 drops of soln + 4 drops of 1%

Glyoxalbis reagent + a drop of 2N

NaOH + a drop of 10% Na2CO3 –

soln + 4 drops of CHCl3. Shake

well and allow it to settle – red

organic layer.

T.V.Rajale

Ca+2

White ppt Ppt. remain insoluble No ppt or Very

slight ppt No Change

Zn+2


colorless solution


colorless solution

Cr+3

Green ppt Ppt dissolves

Co+2

Blue ppt Blue ppt turning pink Green ppt Brown

Pb+2


colorless solution

White ppt Ppt. remain insoluble

Cu+2

Blue ppt Ppt. remain insoluble

( turns brown on standing)

Blue ppt Ppt. dissolve to form

dark blue solution

Fe+2

Dirty Green ppt Ppt. remain insoluble Dirty Green ppt Ppt. remain insoluble

Fe+3

Reddish Brown ppt Ppt. remain insoluble Reddish Brown

ppt

Ppt. remain insoluble

NH4+ No ppt. When

warm NH3 smell

No Change No ppt. No Change

Result :-

1) Acidic radical :- ________and _________

2) Basic radicals :- ________and _________

Probable mixture is:-

a) _____________+______________b)._____________ +____________

T.V.Rajale

Aim :-Estimation ofironfromhematite ore

Principle:Hematite ore contains mainly iron oxide Fe2O3with impurities such as Al2O3 and SiO2.

Fe content above 65-70%. It has little gangue (<6% SiO2 and 3-4% Al2O3) Chemicals :- Conc. HCl ,Conc. HNO3,Perchloric acid 60% ,K3Fe(CN)6 , K2Cr2O7 (0.025N) ,SnCl2 sol.(4%) ,

HgCl2 sol.(saturated).

Procedure:

The dissolution of Ore:

About 0.3-0.4 g of ore is accurately weighed in 250 ml conical flask add to it 15 ml con. HCl. Place a

stem-cut funnel in the mouth of the flask. Heat the flask till the ore is completely dissolved. Cool and add to it

con.HNO3 about 5 ml and heat for 10 minutes. Cool thoroughly and add 5 ml 60% perchloric acid and heat till

white fumes starts evolving. Cool the flask. Filter the above solution through Whattman filter paper No. 41.

Pour and wash the residue with hot water till it is free from acid as tested with litmus paper. Collect the Filtrate

and washing. Dilute-it to 250 ml and reuse for estimation of iron

Estimation of Iron volumetrically

Pipette out 100 ml diluted solution in 500 ml beaker add 3 ml conc. HNO3, 7.5 g of ammonium

Chloride, 5 to 6 drops of bromocresol purple indicator and heat to boiling and add slowly to the above solution

1:1 ammonia till iron is completely precipitated. (i.e. supernent liquid turns purple). Filter through ordinary

filter paper and wash with hot water three times. Dissolve the precipitate in hot 1:1 HCl (About 10 ml) and

wash the filter paper with hot water till free from acid. Dilute the filtrate to 100 ml in volumetric flask. Fill it in

burette 2.

Take out 10 ml of above solution, heat to boiling and add to it 4% SnCl2 solution dropwise till becomes

colourless, add a drop or two drops SnCl2 in excess to ensure the complete reduction. Cool thoroughly and add

solution of HgCl2 till slight turbidity is obtained. Finally titrate with standard K2Cr2O7(0.025 N) using

potassium ferricyanide solution as an external indicator. Calculate % of iron present in Ore.

Iron is estimated using K2Cr2O7 solution by two methods:

A. External Indicator: K3Fe(CN)6 Potassium ferricynide. 1. Fill burette no.1 with diluted solution of iron and burette no.2 with 0.025N K2Cr2O7 solution.

2. Take by burette no.1, 10 ml. of diluted iron solution in a100 ml. conical flask.

3. Add to it 2 ml. conc. HCl and boil it. It becomes yellow in colour. 4. To this hot solution add drop by drop 4% SnCl2 in excess to ensure complete reduction of ferric iron to ferrous

iron.

5. Cool the solution in the flask thoroughly under tap water. 6. To this cooled solution add drop wise saturated solution of HgCl2 till a slight turbidity is just obtained. (Caution:

Avoid excess of HgCl2 otherwise it will oxidize Fe2+

to Fe3+

).

7. Titrate this solution with 0.025N K2Cr2O7 using K3[Fe(CN)6] as an external indicator. The end point of the titration is noted when there is no change in colour of the indicator. Call this reading as X1 ml.

8. In a similar way take two more reading. Find the constant burette reading as X ml.

B. Internal indicator: Diphenyl amine.

Potassium dichromate acts as an oxidizing agent in acidic medium and oxidizes Fe (II) to Fe (III) ions.

Diphenylamine is colorless, so long as K2Cr2O7 is completely used up in the reaction. At the end point, a slight

excess of K2Cr2O7 oxidizes the indicator to intense violet colour.

Reactions:

Fe2O3 + 6HCl 2FeCl3 + 3H2O

2FeCl3 + SnCl2 2FeCl2+ SnCl4

SnCl2+ 2HgCl2 SnCl4 +Hg2Cl2

SnCl2+ HgCl2 SnCl4 +Hg (Gray ppt.)

6FeCl2+14HCl+K2Cr2O7 6FeCl3+2KCl+2CrCl3+7H2O

T.V.Rajale

Observations:

Weight of Ore taken :W=_____gm

a) Burette 2- 0.025K2Cr2O7solution

b) Burette 1 solution – Diluted solution

c) Indicator – K3[Fe (CN) 6]

d) End point –

Calculations:

1000 ml 1N K2Cr2O7 = 55.85 g of Iron.

X ml N1 Normal K2Cr2O7 =? 1 55.85

1000

XxN x

= A g of Iron

10 ml solution = A g of Iron

100 ml solution =? 10

100 xA

= B g of Iron

250 ml solution =? 100

250 xB

= C g of Iron

W g ore samplecontains = C g of Iron

100 g of sample =? 100 xC

W % of Iron in Ore simple = -------% Fe

Result Table:

Sr.No. Description Values

1. Weight of Hematite ore taken W=

2. Amount of Fe in sample

3. % of Fe

Sr.

No.

Burette 1 Solution

(in ml)

Burette 2 reading

(in ml)

Constant Burette reading

(in ml)

1. 10 X1=_____

X ml 2. 10 X2=_____

3. 10 X3=_____

T.V.Rajale

Aim: Estimation of manganese frompyrolusite ore.

Theory :Pyrolusite ore contains a large amount of manganese in the form of manganese dioxide, MnO2, and

little silica. It is a black mineral. Its MnO2 content is between 60 to 63 % and silica content is between l0 to l5%

.Thedissolution of the ore is done in the mixture of conc. HCl and conc.HNO3. The insoluble residue contains

silica (SiO2) and soluble part contains largelymanganese. Silica is estimated gravimetrically while manganese is

estimated volumetrically, using KMnO4. Potassium permanganate is a powerful oxidizingagent in acidic

medium and hence can be used to estimate Mn volumetrically. Themethod is called Volhard's method.

Chemicals: conc. HCl , conc. HNO3 , conc. H2SO4 , Zinc oxide paste (emulsion) ,KMnO4 solution

(approx. 0.1 N) oxalic acid

Apparatus : Stem-cut funnel, Silica crucible , 100 ml. Volumetric flask,burette,etc

Procedure :

Dissolution of the ore :

1. Weigh accurately about 0.3 to 0.4 g of the ore. call it as w g. Transfer it in aconical flask.

2. Add to it l0 ml. conc. HCl and 3 ml. conc. HNO3. cover it with a stem-cut funnel which actsas an air

condenser.

3. Heat the flask in a fuming cupboard on a low flame till black particles of the ore dissolve. Ifthe ore does

not dissolve, again add 2 ml. conc.HCI and 1 ml. conc. HNO3 and heat it again.

4. Repeat the procedure till the ore dissolves.

5. Cool the flask and add 2 ml. conc. H2SO4 slowly from the sides of flask.

6. Heat the flask again till white copious fumes of SO3 start evolving.

7. Cool the solution and rinse the funnel and its stem with little distilled water in the same flask.Add to it

about 20 ml. distilled water.

Filter the above solution through whatman No. 41 filter paper collect the filtrate in a

50ml.beaker. Transfer all the silica in a filter paper. Wash it with hot water till theresidueis

free from chloride (test with AgNO3) and acid (test by blue litmus paper).Collect the filtrate

and washings in the same beaker. Dilute it to exactly 100 ml in avolumetric flask. Preserve it

for the volumetric estimation of Mn. Estimation of Mnyolumetrically (Volhards method)

Principle:

This method is based on the oxidation of divalent manganese with potassium permanganate in a hot (not less than 80°C)

solution neutralised with zinc oxide and containing a little excess of the latter. The endpoint is indicated by the persistent

pink colour.

Solid zinc oxide have a tendency to adsorb manganese ion. Potassium permanganate was stable in boiling hot solution at

pH 7.08 which was obtained by saturation with zinc oxide. Fading in pink of potassium permanganate observed near the

end point of the titration

During the dissolution of pyrorusite ore, MnO2 gets converted to MnSO4i,e, Mn (IV) gets

converted to Mn (II). Volhard,s method is based on the principle that when manganous

salt solution is warmed and titrated with standard KMnO4 solution turns to brown and dark precipitate of

hydrated manganesedioxide is obtained. During the reaction manganous ion is

oxidized and permanganate ion is reduced giving hydrous manganese dioxide.

2KMnO4 + 3MnSO4 + 2H2O K2SO4+ 5MnO2 +2H2SO4

i.e. 3Mn2+

+ 2MnO4-

+ 2H2O 5MnO2 + 4H+

Hydrated manganese dioxide has acidic properties and absorbs manganous hydroxide

Preventing complete oxidation. This difficulty is avoided by introducing sufficient amount of

ZnO paste.

FunctionofZnOpaste(emulsion):

i) The precipitate hydrated of MnO2 settles very quickly.

T.V.Rajale

ii) It neutralisesH2SO4 which is added during the titration of manganese

iii) It avoids formation of potassium permanganate.

iv) It avoids formation of manganous acid, hence prevents precipitation of manganous manganite.

v) It forms Zn ferrite with Fe if present as an impurity in MnSO4. Thus interference of Fe is

masked.

Reactions:

MnO2 + 4HC1 MnC12 + 2H2O + Cl2

MnO2 + 4HNO3 Mn(NO3)2 + 2H2O + 2NO2 +O2

MnCl2 + H2SO4 MnSO4 + 2HC1

Mn(NO3)2 + H2SO4 MnSO4 + 2HNO3

2KMnO4 + 3MnSO4 + 2H2O 5MnO2 + K2SO4 +2H2SO4

stateoxidation in change5

3 Wt.x Atomic

x

ZnO + H2SO4ZnSO4 + H2O

Procedure:

Part I -Preparation of standard 0.1N Oxalic acid solution (Eq. Wt.63)

1000 ml 1N oxalic acid solution contains 63 g of oxalic acid.

1000 ml 0.1N oxalic acid solution contain 6.3 g of oxalic acid.

250ml 0.1N oxalic acid solution contain 1.575 g of oxalic acid.

Weigh accurately 1.575 g of oxalic acid (H2C2O4.2H2O) on a watch glass. Transfer it in a beaker and rinse the

watch glass with little water in the same beaker. Dissolve it in about 50ml distilled water. Transfer it into 250 ml

volumetric flask. Dilute it up to the mark using distilled water. Use of this solution for standardization KMnO4

solution.

Part II :Standardisation of KMnO4solution :

1. Fill burette no.1 by 0.1 N (approx.)KMnO4solution.Fill burette no.2 by 0.1 N oxalic acid Take by burette no.2, 10

ml of 0.1 N oxalic acid and add to it 15 ml 2N H2SO4solution

2. Heat the solution on a wire gauze to 70o C and titrate this hot solution with KMnO4 solution added from burette

no.1. 3. The end point of the titration is noted when permanent faint pink colourappears.Call this

4. burette reading as X1 ml.

5. To the same solution, add 2 ml oxalic acid solution by burette no.2 and heat the flask to 6. 70

oC.The solution becomes colorless.

7. To this hot solution, add KMnO4solution from burette no.1 till faint pink colour appears.

8. Call this burette reading as X2 ml.

9. To the same solution, add 2 ml oxalic acid solution by burette no. 2 and heat the flask to 70oC.The solution

becomes colorless.

10. To this hot solution, add KMnO4 solution from burette no.1 till faint pink colour appears.

11. Call this burette reading as X3 ml. 12. From these three burette readings find out the exact normality of KMnO4 solution.

T.V.Rajale

Part III : Estimation of Manganese :

Fill the burette no.1 by standardized KMnO4solution.and burette no.2 with diluted solution

of MnSO4.

1. Take by burette no.2, 10 ml of the diluted solution of MnSO4. Add 1/2 test tube of ZnO paste.

2. Add one test tube water to it. 3. Heat the solution on water bath between 40 and 60

0C and add 2 to 3 drops of 2N HNO3 solution (which promotes

the settling of the ppt. of MnO2 at the bottom).

4. Titrate this hot solution with standardised KMnO4 solution from burette no.1 with constant shaking.The end point is faint pink colour to supernatant liquid which persists even after vigorousshaking. Note

down this burette reading . The faint pink colour should remain as it is even after heating, if not add one or two

drops of KMnO4 solution.

5. Take two more readings. Find the constant burette reading as Y ml.

Imp. Note : During the titration it is necessary allow the ppt. to settle down and see the colour of

the supernatant liquid against white background after each reading.

Observation and Observation Table –

Standardisation of KMnO4 solution –

Burette 1 : 0.1 N (approx) KMnO4 solution

Burette 2 : 0.1 N H2C2O4 . 2H2O solution

Indicator : KMnO4 act as a self-indicator

End Point : Colourless to pink

Burette – 2 10 ml 12 ml 14 ml

Burette – 1 X1 = ml X2 = ml X3 = ml

Calculations:-

Find out exact normality of KMnO4

KMnO4 = Oxalic acid

N1x X1 = 0.1 x 10 ∴N1 =1

101.0

X

x

N2 x X2 = 0.1 x 12 ∴N2 = 2

121.0

X

x

N3 x X3 = 0.1 x 14 ∴N3 = 3

141.0

X

x

Exact normality of KMnO4= mean N4 = 3

321 NNN

T.V.Rajale

Estimation of Mn from a given solution –

Observation and Observation Table –

Burette 1 : 0.1 N (approx) KMnO4 solution

Burette 2 : diluted Mn2+

solution

Indicator : KMnO4 act as a self-indicator

End Point : Colourless to pink

Burette – 2 10 ml 10 ml 10 ml C.B.R

Burette – 1 Y1 = ml Y2 = ml Y3 = ml Y=___ml

Estimation of Manganese: (Volumetrically)

1000 ml 1 N KMnO4 = 16.462 g of Mn.

Y ml N4Normal KMnO4 = ? 1000

x16.46N4Yx

= Z g of Mn.

10 ml dil. solution = Z g of Mn. 100 ml dil. solution = ?

100

10

Zx

= A g of Mn

W g of ore = A g of Mn

100 g of ore = ? W

Ax100

% of Mn = ---- %

Result Table:

Sr.No. Description

Values

1. Weight of Pyrolusite taken

2. Exact Normality of KMnO4

3. Amount of Mn in sample

4. % of MnO2

T.V.Rajale

Aim: Estimation of calciumfromdolomite ore.

Principle :The mineral dolomite has a theoretical composition of 40-65% CaCO3 and 40-45% MgCO3.

Part I -Preparation of standard 0.1N Oxalic acid solution (Eq. Wt.63)

1000 cm3 1N oxalic acid solution contains 63 g of oxalic acid.

1000 cm3 0.1N oxalic acid solution contain 6.3 g of oxalic acid.

250cm3 0.1N oxalic acid solution contain 1.575 g of oxalic acid.

Weigh accurately 1.575 g of oxalic acid (H2C2O4.2H2O) on a watch glass. Transfer it in a beaker and

rinse the watch glass with little water in the same beaker. Dissolve it in about 50 cm3 distilled water.

Transfer it into 250 cm3 volumetric flask. Dilute it up to the mark using distilled water. Use of this

solution for standardization KMnO4 solution.

Part II :Standardisation of KMnO4solution :

i) Wash and clean burette I and burette II with water.

ii) Rinse and fill the burette I with approx. KMnO4 solution (remove the air bubble) and place it at LHS.

iii) Rinse and fill the burette II with 0.1N oxalic acid solution (remove the air bubble) and place it at RHS.

iv) Take by burette II, 10 cm3 of 0. 1 N oxalic acid and add to it 15 cm

3 2N H2SO4solution in conical flask

v) Heat the solution on a wire gauze to 70oC( just bubbles starts) and titrate this hot solution with

KMnO4solution added from burette I. The end point of the titration is noted when permanent faint pink

color appears. Call this burette reading as X1cm3.

vi) To the same solution, add twocm3 oxalic acid solution by burette II and heat the flask to 70

oC.The

solution becomes colorless.

vii) To this hot solution, add KMnO4solution from burette I till faint pink colour appears. Call this burette

reading as X2cm3.

viii) To the same solution, add twocm3 oxalic acid solution by burette II and heat the flask to70

oC.The

solution becomes colorless.

ix) To this hot solution, add KMnO4 solution from burette I till faint pink colour appears. Call this burette

reading as X3cm3.

x) From these three burette readings find out the exact normality of KMnO4 solution.

Part III : Estimation of Calcium:

i) Weigh about 0.3-04g of ore accurately and record the weight of the ore.Transfer the powder in 250 cm3

beaker.

ii) Dissolve the ore in 10 cm3conc.HCl and 20-30cm

3distilled water .Heat the solution to boil for

10minutes.Cool the solution and filter it.

iii) Collect the filtrate in beaker. Discard the residue. 2.5 per cent oxalic acid are added and the solution is

brought to the boiling point and kept gently boiling until the calcium oxalate is coarsely granular.

Three per cent ammonium oxalate is then added, a few drops at a time, to the boiling solution, waiting

after each addition until the resulting precipitate has become coarsely crystalline. The amount of

ammonium oxalate to be added depends on the amount of calcium in solution. Twice the amount

necessary to combine with all the calcium is sufficient. After the calcium oxalate has become coarsely

crystalline and has settled to the bottom of the flask, it should be frequently stirred up in the liquid to

prevent the latter from boiling over suddenly. After the precipitate has become crystalline and has

settled, the solution is allowed to cool to room temperature.

iv) Again dissolve the precipitate.10 cm3conc.HCl and 20-30cm

3distilled water .Heat the solution to boil for

10minutes.Cool the solution.

v) Transfer it to 100cm3 volumetric flask. Wash the beaker and rod with distilled water and transfer the

washings to volumetric flask. Dilute the solution to 100cm3 with distilled water. Shake the solution.

vi) Wash and clean burette II with water.

vii) Rinse and fill the burette II with diluted solution of calcium (remove the air bubble) and place it at RHS.

T.V.Rajale

viii) Fill the burette I with approx. KMnO4 solution.

ix) Take by burette II, 10 cm3 of diluted solution of calcium and add to it 15 cm

3 2N H2SO4solution in

conical flask

x) Heat the solution on wire gauze to 70o C (just bubble starts) and titrate this hot solution with KMnO4

solution added from burette I.

xi) The end point of the titration is noted when permanent faint pink color appears. Call this burette reading

as Y cm3.

xii) Repeat the step vii to ix for two more reading and record the constant burette reading as Y cm3

Observation

Weight of ore =________ g

Observation table

For standardization of KMnO4

i) Solution in burette I (LHS)= KMnO4 solution

ii) Solution in burette II (RHS)= 0.1N oxalic acid solution

iii) Indicator = KMnO4 ( Self indicator)

iv) End point = Colorless to pink.

Burette II (RHS)

0.1N oxalic acid

10cm3 12cm

3 14cm

3

Burette I (LHS)

KMnO4

X1 = X2 = X3 =

2KMnO4+CaC2O4+4H2SO4⟶ 2MnSO4+K2SO4+CaSO4+2CO2+4H2O

Calculations:-

Find out exact normality of KMnO4

KMnO4 = Oxalic acid

N1x X1 = 0.1 x 10 ∴N1 =1

101.0

X

x

N2 x X2 = 0.1 x 12 ∴N2 = 2

121.0

X

x

N3 x X3 = 0.1 x 14 ∴N3 = 3

141.0

X

x

Exact normality of KMnO4= mean N4 = 3

321 NNN

T.V.Rajale

Observation table

For Estimation of Calcium:

i) Solution in burette I (LHS)= KMnO4 solution

ii) Solution in burette II (RHS)= diluted solution of calcium

iii) Indicator = KMnO4 ( Self indicator)

iv) End point = Colorless to pink.

Burette II (RHS)

diluted solution of calcium

10cm3 10cm

3 10cm

3 C.B.R

Burette I (LHS)

KMnO4

____ cm3 ____ cm

3 ____ cm

3 Y= ____ cm

3

1000 cm3 1N KMnO4 = Equivalent weight of calcium

= 20.04g

∴ Y cm3 N4 N KMnO4 =

1000

04.20 4 xYNx = A g of calcium

i.e. 10 cm3 diluted solution contains = A g of calcium

∴100 cm3 diluted solution contains = A x 10= B g of calcium

i.e. W g of ore contains = B g of calcium

∴ 100 g of ore contains =W

xxB 10010= % of Ca

Result :

1. Weight of Ore W =_____ g

2. Exact normality of KMnO4 N4 =______N

3. Weight of calcium in ore =______g

4. % Ca in given ore = ____%.

T.V.Rajale

Aim:-Estimation of tin by gravimetric from solder alloy Requirements: Conc. HN03, Whatman filter paper No. 40 Silica crucible ,

Procedure: Dissolution of the alloy :

i) Weigh accurately about 0.3 to 0.5 g of the ore.Call it as W g. Transfer it in a conical flask.

ii) Add to it 15 ml. conc. HNO3 and 10 ml. of distilled water. Cover it with a stem-cut funnel which acts as an

air condenser.

iii) When the vigorous reaction stops, then evaporate solution on a sand bath, till metallic and white precipitate

forms. (Take care that the solution does not evaporate alloy dissolves completely).

iv) Add 50 ml of distilled water to the precipitate in the beaker. Boil for 20 minutes with constant stirring on

water bath. Allow it to cool.

v) Filter the solution through a Whatman filter paper No. 40 and collect the filtrate in a 250 ml volumetric flask.

vi) Wash the precipitate on the filter paper 3-4 times with1% HNO3 solution and then with distilled

water.(Preserve residue).

(A) Estimation of Tin:

(1) Dry the residue obtained from step Nos. v and vi in an electric oven at 110oC.

(2) Ignite the dried residue along with the filter paper in a previously weighed silica crucible. Heat

it for about 30 minutes and then cool'

(3) Weigh the residue of tin as SnO2.

Amount of tin :

1) Weight of empty crucible =w1=

2) Weight of crucible+residue =w2=

3) weight of residue (SnO2) be = w2-w1= x g.

Now, 150.7 g of SnO2 = 118.7 gms of Tin.

118.7 X x

... x g of SnO2 = --------------- gms of Tin

150.7

= A gm of Tin.

W g of the alloy contains = A gm of Tin.

A x 100

... 100 g of the alloy contain =- ---------------

W

... Percentage of tin = ………….. %

Results:-


1. Weight of Solder

2. Amount of Sn in sample

3.

% of Sn

T.V.Rajale

Estimation of Znvolumetrically from brass alloy

Requirements: Brass sample, Conc. HN03, 0.01M EDTA solution, hexamine , indicator Xylenol orange,

EBT indicator, buffer solution

Dissolution of the alloy :

1) Weigh accurately about 0.3 to 0.5 g of the ore.Call it as W g. Transfer it in a conical flask.

2) Add to it 15 ml. conc. HNO3 and 10 ml. of distilled water. Cover it with a stem-cut funnelwhich acts as an

air condenser.

3) When the vigorous reaction stops, then evaporate solution on sand bath add 5mlconcHCl

4) Cool the flask and add 50 ml of distilled water to it.

5) Pass H2S gas for complete precipitation of copper and filter it and collect the filtrate (colorless).

6) Check filtrate by passing H2S gas to remove copper completely.

7) Dilute the filtrate up to the mark in 100ml volumetric flask and use as diluted Zn stock solution.

Part II :Standardisation of EDTA solution :

1) Fill burette no.1 by 0.01 M (approx.) EDTA solution.

2) Fill burette no.2 by 0.01 M ZnSO4

3) Take by burette no.2, 10 ml of 0.01 M ZnSO4 and add to it one test tube distilled water Add half test

4) tube buffer solution ( pH=10) and 2-3 drops of EBT indicator

5) Titrate this solution with EDTA solution added from burette no.1.

6) The end point of the titration is noted from wine red to blue colour appears. Call thisburette reading as X1

ml.

7) To the same solution, add 2 ml ZnSO4solution by burette no.2 and The solution becomeswine red.

8) Add EDTAsolution from burette no.1 till faint wine red to blue colourappears.Call this burette reading as X2

ml.

9) To the same solution, add 2 ml ZnSO4 solution by burette no. 2 and.The solutionbecomes wine red.

10) Add EDTA solution from burette no.1 till wine red to blue colourappears.Call this burette reading as X3 ml.

11) From these three burette readings find out the exact molarity of EDTA solution.

Estimation of Zn by EDTA method:

1. Fill the burette no.1 by standardized EDTA solution and burette no.2 with diluted solution of Zn

2. Take 10ml of stock solution from burette no.2 in conical flask. Add one test tube distilled water to it.

Add 5-6 drops of Xylenol orange indicator to it

3. Now add hexamine powder till color changes from yellow to wine red which indicates that pH is raised to

about 6.

4. Titrate it against 0.01M EDTA solution from the burette no.1 End point will be form wine red to Yellowof

color. Call this burette reading as Y1 ml.

5. Repeat steps 2 to 4 for two more reading Y2 ml and Y3 ml.

T.V.Rajale

Weight of Brass alloy taken W= _____________gm ( after decimal three digit)

Observation table

For standardization of EDTA

i) Solution in burette I (LHS)= EDTA solution

ii) Solution in burette II (RHS)= 0.01N ZnSO4solution

iii) Indicator =EBT indicator

iv) End point = wine red to blue

Burette II (RHS)

10cm3 12cm

3 14cm

3

Burette I (LHS) X1 = X2 = X3 =

Calculations:-

Find out exact normality of EDTA

EDTA ≡ ZnSO4.7H2O

M1V1 = M2V2

M1x X= 0.01x 10

M1 = 1

22

X

VM =

1

1001.0

X

x

M2 = 2

1201.0

X

x

’

M3 = 3

1401.0

X

x

Exact morality of EDTA = M1+M2+M3 =M4

3

For Estimation of Zinc:

i) Solution in burette I (LHS)= EDTA solution

ii) Solution in burette II (RHS)= diluted solution of Zinc

iii) Indicator = Xylenol orange indicator

iv) End point = wine red to Yellow

Burette II (RHS)

10cm3 10cm

3 10cm

3 C.B.R

Burette I (LHS) ____ cm3 ____ cm

3 ____ cm

3 Y= ____ cm

3

T.V.Rajale

A) Amount of Zn :

10 ml of the stock solution required y ml of M4 EDTA solution.

1000 ml of 1M EDTA = 65.37 gms of Zn

65.37 x Y x M4

...y ml of M4 EDTA = 1000 x 1 gms of Zn

= A g of Zn

... 100 ml Zn diluted solution contains =Ax 10 =B gms of Zinc

__W___ g of the alloy contains = B gams of Zn

B x 100

... 100 g of the alloy contain = -------------------------

W weight of the alloy

= ………. %

Results:-


1. Weight of Brass

2. Exact Molarity of EDTA

3. Amount of Zn in sample

4. % of Zn

binary mixtures containing common anions - pca.ac.inpca.ac.in/uploaded_files/t.y.b.sc inorganic...

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