Qualitative analysis of salts lab manual MANIK

Laboratory Manual
Course Code: PHARM 2114
Course Title: Inorganic Pharmacy-II Lab
Prepared By
Shadiduzzaman and Md. Imran Nur Manik
Lecturer
Department of Pharmacy
Northern University Bangladesh
Edited By
Somaia Haque Chadni
Lecturer
Department of Pharmacy
Northern University Bangladesh

2114: Inorganic Pharmacy-II Lab
Prepared By: Shadiduzzaman and Md. Imran Nur Manik
Edited By: Somaia Haque Chadni
Lecturer; Department of Pharmacy; Northern University Bangladesh (NUB).
Sl.
No.
Date Name of the experiment
Page
No.
01.
Conversion of different water insoluble or sparingly soluble
substances into water soluble form. 01 – 06
02-A
Qualitative analysis (identification) of anions from inorganic salt
solutions. 07 – 10
02-B Qualitative analysis (identification) of group I & group II cations. 11 – 14
02-C Qualitative analysis (identification) of group III cation. 15 – 19
02-D Qualitative analysis (identification) of group IV & group V cations. 20 – 22
Md.
Imran
Nur
Manik

2114: Inorganic Pharmacy -II Lab
Prepared By: Shadiduzzaman and Md. Imran Nur Manik Edited By: Somaia Haque Chadni Page 1
Experiment No. 01
Name of the Experiment: Conversion of different water insoluble or sparingly soluble
substances into water soluble form.
Principle:
Solubility, the phenomenon of dissolution of solute in solvent to give a homogenous
system, is one of the important parameters to achieve desired concentration of drug in
systemic circulation for desired (anticipated) pharmacological response. Low aqueous
solubility is the major problem encountered with formulation development of new
chemical entities as well as for the generic development. More than 40% new chemical
entities developed in pharmaceutical industry are practically insoluble in water. Any drug
to be absorbed must be present in the form of solution at the site of absorption. Various
techniques are used for the enhancement of the solubility of poorly soluble drugs which
include physical and chemical modifications of drug and other methods like particle size
reduction, crystal engineering, salt formation, solid dispersion, use of surfactant,
complexation, and so forth. Selection of solubility improving method depends on drug
property, site of absorption, and required dosage form characteristics.
Terminologies:
A solution may be defined as a homogeneous mixture of two or more components that
form a single phase.
The component that determines the phase of the solution is termed the solvent and
usually constitutes the largest proportion of the system. The other components dispersed
as molecules or ions throughout the solvent are termed solutes.
The transfer of molecules or ions from a solid state into solution is known as dissolution.
The extent to which the dissolution proceeds under a given set of experimental conditions
is referred to as the solubility of the solute in the solvent.
Solution Process
In order to dissolve a solid, the particles of the solvent must be able to separate the
particles of the solute and occupy the intervening space. This happens when the positive
end of the solvent molecule approaches the negative end of the solute molecule. The
solute molecule is pooled in the solution when the force between the solvent solute
molecules overcomes the attractive forces between the solute molecules themselves.
Therefore, the solute will be soluble in the solvent if the solute-solvent attraction is
stronger than the solvent-solvent attraction and solute-solute attraction.
H1 H2
H3
Figure: A molecular view of the solution process. The solute
molecules and solvent molecules first being spread apart,
and then being mixed together. The relative strength of
forces holding solvent molecules togetherH1, solute
particles togetherH2, and the forces between solvent and
solute molecules H3 in the solution are important in
determining the solubility.
Md.
Imran
Nur
Manik

An ionic solid dissolves in water because the number of water molecules around the
surface is greater than the number of other ions of the solid. The attraction between polar
water molecules and a charged ion enables the water molecules to pull ions away from the
crystal, a process called dissolving.
A General Solubility Rule:
Polar molecules are soluble in polar solvents e.g. C2H5OH in H2O. Thus polar compounds,
like table sugar (C12H22O11), are soluble in polar solvents and insoluble in non-polar
solvents. On the other hand non-polar molecules are soluble in non-polar solvents e.g.
CCl4 in C6H6.
Accordingly non-polar compounds, like naphthalene (C10H8), are soluble in non-polar
solvents and insoluble in polar solvents.
This it the like dissolves like rule.
Factors Affecting Solubility of a Solute
Temperature
Generally in many cases solubility increases with the rise in temperature and decreases
with the fall of temperature but it is not necessary in all cases. However we must follow
two behaviours:
In endothermic process solubility increases with the increase in temperature and vice
versa.For example: solubility of potassium nitrate increases with the increase in
temperature.
In exothermic process solubility decrease with the increase in temperature.
For example: solubility of calcium oxide decreases with the increase in temperature.
Effect of pressure
The effect of pressure is observed only in the case of gases. An increase in pressure
increases of solubility of a gas in a liquid. For example CO2 is filled in cold drink bottles
(such as coca cola, Pepsi 7up etc.) under pressure.
Chemical natures of the solute and solvent
A polar solute will dissolve in a polar solvent but not in a non-polar solvent. The adage
"like dissolves like" is very useful. Example: Alcohol (polar substance) dissolves in water
(polar substance). Water (polar substance) does not dissolve in oil (non-polar substance)
Stirring
With liquid and solid solute, stirring brings fresh portions of the solvent in contact with
the solute, thereby increasing the rate of dissolution.
Amount of solute already dissolved
When there is little solute already in solution, dissolving takes place relatively rapidly. As
the solution approaches the point where no solute can be dissolved, dissolving takes place
more slowly.
Molecular size
The larger the molecules of the solute are, the larger is their molecular weight and their
size. If the pressure and temperature are the same than out of two solutes of the same
polarity, the one with smaller particles is usually more soluble.
Md.
Imran
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Manik

Methods for Expression of Concentration
Expression Symbol Definition
Mole Fraction X
Ratio of moles of one constituent of a solution to the
total moles of all constituents (solute & solvent)
Mole percent
Moles of one constituent in 100 moles of the solution.
It is obtained by multiplying by 100X
Percent by weigh
%W/W 100
SolutionofMass
SoluteofMass

Percent by volume
%V/V 100
SolutionofVolume
SoluteofVolume

Percent by
weight-in-volume %W/V 100
SolutionofVolume
SoluteofMass

Percent by
volume-in-weight %V/W 100
SolutionofWeight
SoluteofVolume

Parts By Mass
(Solid in solid)
FactortionMultiplica
SolventofMass
SoluteofMass

Parts per million ppm Multiplication Factor=106
Parts per billion ppb Multiplication Factor=109
Solubility Definitions
Description Parts of Solvent required to dissolve 1 part of Solute
Very Soluble Less than 1 part
Freely Soluble from 1 to 10 parts
Soluble from 10 to 30 parts
Sparingly Soluble from 30 to 100 parts
Slightly Soluble from 100 to 1000 parts
Very Slightly Soluble from 1000 to 10,000 parts
Practically Insoluble more than 10,000 parts
Approximate quantity of solvent by volume for one part of soluble by weight.
For example, 1g of a very soluble substance dissolves in less than 1ml of solvent.
Importance of Solubility in Pharmacy
Solubility is one of the important parameters to achieve desired concentration of drug in
systemic circulation for achieving required pharmacological response. Poorly water soluble
drugs often require high doses in order to reach therapeutic plasma concentrations after
oral administration.
Most of the drugs are either weakly acidic or weakly basic having poor aqueous solubility.
These poorly water soluble drugs having slow drug absorption leads to inadequate and
variable bioavailability and gastrointestinal mucosal toxicity.
For orally administered drugs solubility is the most important one rate limiting parameter
to achieve their desired concentration in systemic circulation for pharmacological
response.Solubility also plays a major role for other dosage forms like parenteral
formulations as well.
Md.
Imran
Nur
Manik

Apparatus
1. Test tubes
2. Pipette
3. Dropper
4. Bunsen Burner
5. Watch glass
Reagents
1. Solid Sample
a. Salicylic acid
b. Benzoic acid
2. Chemicals
a. Sodium Carbonate (Na2CO3)
b. Sodium Hydroxide (NaOH)
3. Distilled water
Salicylic acid
Solubility: 1 gm in 460m ml water
Conversion Reaction:
2+Na2CO3 2+CO2 + H2O
Procedure:
1. Take a small amount of salicylic acid (0.5 g) in a dry test tube.
2. Add a small volume of water (1 ml) and shake well. Observe that whether it is
dissolving or not.
3. Now add small amount of Sodium carbonate (Na2CO3) and shake well.
4. Observe that whether it is dissolving or not.
5. Continue the shaking for complete dissolution.
Pharmaceutical uses of Salicylic Acid (Salicylic Acid Topical)
Uses
This medication is used on the skin to treat common skin and foot1.
(plantar) warts. Salicylic acid helps cause the wart to gradually peel off.
This medication is also used to help remove corns and calluses.2.
Topical salicylic acid is used to help clear and prevent pimples and skin blemishes3.
in people who have acne.
Md.
Imran
Nur
Manik

Topical salicylic acid is also used to treat skin conditions that involve scaling or4.
overgrowth of skin cells such as psoriasis (a skin disease in which red, scaly
patches form on some areas of the body), ichthyoses (inborn conditions that cause
skin dryness and scaling), dandruff, corns, calluses, and warts on the hands or
feet.
Topical salicylic acid should not be used to treat genital warts, warts on the face,5.
warts with hair growing from them, warts in the nose or mouth, moles, or
birthmarks.
Salicylic acid is in a class of medications called keratolytic agents.6.
Topical salicylic acid treats acne by reducing swelling and redness and unplugging7.
blocked skin pores to allow pimples to shrink.
It treats other skin conditions by softening and loosening dry, scaly, or thickened8.
skin so that it falls off or can be removed easily.
Market preparations of Salicylic Acid
Sl. Brand Name Company
Benzoic acid
Solubility: 1 gm in 300 ml water
Conversion Reaction:
Procedure:
1. Take a small amount of benzoic acid (0.5 g) in a dry test tube.
2. Add a small volume of water (1 ml) and shake well. Observe that whether it is
dissolving or not.
3. Now add small amount of Sodium hydroxide (NaOH) and shake well.
4. Observe that whether it is dissolving or not.
5. Continue the shaking for complete dissolution.
Md.
Imran
Nur
Manik

Pharmaceutical uses of Benzoic Acid
Uses
1. Benzoic acid helps prevent infection caused by bacteria.
2. Benzoic acid and salicylic acid topical (for the skin) is a combination medicine used
to treat skin irritation and inflammation caused by burns, insect bites, fungal
infections, or eczema.
3. As an inactive ingredient in the pharmaceutical industry, it is used as
a. Antimicrobial preservative,
b. Antifungal, and
c. Tablet and capsule lubricant.
4. Benzoic acid has been used in combination with salicylic acid, as in Whitfield's
ointment, for use as an antifungal for athlete's foot and ringworm.
Brand names of Benzoic Acid
Sl. Brand Name Company
Precautions
Md.
Imran
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Manik

SAFETY FIRST!
In this lab, observe all precautions, especially the ones
listed below. If you see a safety icon beside a step in the
Procedure, refer to the list below for its meaning.
01:Wear your safety goggles. (All steps.)
02:Never cover the opening of a test tube with your finger when mixing chemicals in the
tube. To mix the contents, “flick” the tube. Do not shake carelessly.
03:Silver, barium, and oxalate compounds are poisonous. Avoid contact with these
chemicals.
04:Silver nitrate will stain skin and clothing.
05:Never pick up a dropper bottle by its cap. Always hold a dropper with the tip
lower than the rubber bulb so that the liquid does not run into the bulb.
06:Exercise care when working with a hot water bath.
07:Nitric acid, HNO3, is a strong acid, and is a corrosive and toxic substance which can
cause severe burns and discoloration of the skin. Avoid contact with your skin, eyes, and
clothing. If you do spill some on yourself, wash immediately with plenty of cold water.
Notify your instructor.
08:Sulfuric acid, H2SO4, is a strong acid, and is a corrosive and toxic substance which can
cause severe burns. Avoid contact with your skin, eyes, and clothing. If you do spill some
on yourself, wash immediately with plenty of cold water. Notify your instructor.
09:Silver nitrate, AgNO3, is a toxic substance which can cause burns and discoloration of
the skin. Avoid contact with your skin, eyes, and clothing. If you do spill some on
yourself, wash immediately with plenty of cold water. Notify your instructor.
10:Return or dispose of all materials properly.
11:Wash your hands thoroughly after completing this experiment.
Md.
Imran
Nur
Manik

Experiment No. 02-A
1. Name of the Experiment
Qualitative analysis (identification) of anions from inorganic salt solutions.
2. Principle
Salts are compounds which are formed from the reaction between acids and bases.
An inorganic salt is just a salt which has no organic part in its molecular structure.
Any salt is composed of two parts – cation and anion. The cation part usually comes from
the base and the anion part usually comes from the acid. As a result, most of the common
anions are also called acid radicals.
Some of the most common acid radicals are sulfate (SO4
2–), chloride (Cl–), bromide (Br–),
iodide (I–) and nitrate (NO3
–) which come from H2SO4, HCl, HBr, HI, HNO3 respectively.
Identification of these radicals in an unknown salt sample is done by taking advantage of
the fact that, not all salts of the radicals are highly soluble in water. For example, BaSO4
is poorly water-soluble but BaCl2 has good water solubility. So, if sulfate ion is present in
a sample, addition of BaCl2 will cause formation of precipitate.
Test Principle Reactions
Sulphate
test
principle
Sulphate salt of barium is
insoluble in water and forms
white precipitate, but other
salts of barium are soluble in
water.
So, if addition of BaCl2 causes
formation of precipitate, then
sulphate is present.
SO4
2 + BaCl2 BaSO4 + 2 Cl
(soluble) (white ppt.)
HCl is required to remove any carbonate ion
that may be present (because carbonate ion
also produce white PPT with BaCl2).
Instead of HCl, HNO3 can be used but not
H2SO4.
Halide
test
principle
Silver salts of chloride,
bromide and iodide are
insoluble in water, with
solubility decreasing from
chloride salt to iodide salt. So,
addition of silver nitrate will
cause formation of precipitate
(white/cream/yellow).
When ammonium hydroxide is
added, some of the silver ions
will form soluble
diamminesilver(I) ions.
Thus the insoluble salt will
become soluble. But silver
iodide salt is so insoluble that
even concentrated ammonium
hydroxide can’t dissolve it.
(soluble) (ppt.)
X + AgNO3 AgX + NO3

Chloride,bromide, and iodideions will give
white, pale cream, and pale yellowPPT. will
be formed.
When ammonium hydroxide is added, the
following reaction moves to the right:
Ag+
+NH4OH ⇌ [Ag(NH3)2]+
As a result, the amount of free ions in the
solution will decrease. So, the following
reaction will move to the right.
AgX Ag+ + X
(insoluble) (soluble)
As a result, the salt will be solubilized. But,
in case of silver bromide, concentrated
ammonium hydroxide is required to
significantly dissolve the salt. And for silver
iodide, it is not possible to dissolve it even
with conc. ammonium hydroxide.
Md.
Imran
Nur
Manik

Nitrate
test
This is known as the Ring test
of Nitrate.
In this test, a brown colored
ring is formed between two
layers of acid and ferrous
sulphate solution in a test
tube if nitrate ion is present.
NO3
- + 3 Fe2+ + 4 H+ NO + 3 Fe3+ + 2H2O
[Fe(H2O)6]2+SO4
2- + NO [Fe(H2O)5NO]2+SO4
2- + H2O
Nitrosoferrous sulfate
(brown)
Addition of acid (such as sulphuric acid or
hydrochloric acid) will reduce the nitrate to
NO.
This NO will then attack the ferrous ions to
form nitrosoferrous complex which resides in
the interface of the acid layer and ferrous
sulphate layer.
Acetate
ion
(Ferric
chloride
test)
When ferric chloride solution
is added to the salt solution
reddish brown colour(brick
red) forms.
On the addition of dil. HCl the
color disappears (PPT forms).
Boiling the brick red colored
solution so formed,followed by
the addition of water reddish
brown PPT forms.
The reddish color is due to the formation of
(CH3COO)3Fe.
The reddish brown precipitate is due to the
formation of (CH3COO)(OH)2Fe.
3. Required apparatus
1. Test tubes
2. Pipette (5mL)
3. Water bath or ice bath
4. Required reagents
1. For sulphate identification
a. Dilute (6M) Hydrochloric acid (HCl)
b. 0.1M Barium chloride (BaCl2) or Barium nitrate {Ba(NO3)2} solution
2. For halide ions identification
a. Dilute nitric acid (2M)
b. 5% Silver nitrate (AgNO3) solution
c. Dilute ammonium hydroxide solution (2M)
d. Concentrated ammonium hydroxide solution (~9M)
3. For nitrate ion identification
a. Concentrated Hydrochloric acid (37%) {/Conc. Sulphuric acid }
b. 5% Ferrous sulphate (FeSO4) solution
4. For Acetate ion identification
a. Dilute Hydrochloric acid
b. 0.2M Ferric chloride (FeCl3) solution
Md.
Imran
Nur
Manik

5. Procedure
5.1 Test for sulphate ion
1. Take 3-4mL of the supplied salt solution in a test tube.
2. Add 2mL of dilute (6M) hydrochloric acid solution to the test tube.
CAUTION:Take special care when handling hydrochloric acid, it is extremely
corrosive. Add slowly to the side wall of the test tube.
3. Add 0.5mL of 0.1M Barium chloride or Barium nitrate solution slowly using the
pipette. Check to see if white precipitate is formed.
4. Add more Barium salt solution if precipitate doesn’t form initially or only small
precipitate is obtained initially.
5.2 Test for halide ions
1. Take 2mL of the supplied salt solution in a test tube.
2. Add 2mL of dilute nitric acid to the test tube.
CAUTION:Be careful when handling nitric acid. Add slowly to the side wall of the
test tube.
3. Add 0.5mL of 5% silver nitrate solution. Check to see if white/Cream/Pale Yellow
precipitate is formed.
4. Add more silver nitrate solution if precipitate doesn’t form initially or only small
precipitate is obtained initially.
5. If precipitate is formed, add dilute ammonium hydroxide solution. Check to see if
precipitate dissolves.
6. If precipitate doesn’t dissolve, add concentrated ammonium hydroxide solution.
Check to see if precipitate dissolves.
5.3 Test for nitrate ion
2. Add concentrated hydrochloric acid as such that salt solution: Conc. HCl is 2:1.
3. Cool it.
NOTE: You can use a water bath or ice bath for this.
4. Add 5mL of 5% ferrous sulphate solution very carefully with a pipette to the side
wall of the test tube.
5. The ferrous sulphate solution should form a layer above the acidic solution.
6. Check to see if a brown ring is formed at the interface of the two layers.
5.3 Test for acetate ion
2. Add 0.2M ferricchloride solution drop-wise.
3. Reddish color (brick red) forms.
4. (If PPT appears) Filter and divide the filtrate into two portions.
5. To one part, add dilute hydrochloride acid solution
6. Reddish color disappears.
7. To second part, add water and boil.
8. Reddish brown precipitate appears.This confirms the presence of acetate ion.
Md.
Imran
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Manik

6. Inference
Name of
the test
Observation Inference
Sample 1 Sample 2 Sample 3
Sulphate
Halide
Nitrate
Acetate
7. Result
8. Precautions
Specimen: Writinginference
Confirmation test for Acid Radicals
Experiment Observations Inference
2 ml of the supplied sample solution was taken in
a test tube. Then 0.5 ml 5% AgNO3 was added to
the sample solution, followed by 2ml dil. HNO3.
White PPTwas formed.
Reaction:Cl–
(aq)+Ag+
(aq)AgCl(s)
White PPT Cl–
Present
Then excess aq. NH3 (2M) solution was added to
it.
PPTdissolved in excess 2M NH3.
AgCl(s)+2NH3
+
(aq) ⇌ [Ag(NH3)2]+
(aq)+ Cl–
Md.
Imran
Nur
Manik

Experiment No. 02-B
Qualitative analysis (identification) of group I& group II cations.
2. Principle
the base and the anion part usually comes from the acid.
Based on solubility characteristics, the common inorganic cations (usually metal in
nature) are classified into five groups. Cation of each group is precipitated by a common
reagent.
So, by step-wise addition of those reagents, we can first identify which group the cation
belongs to. Then by using specific reagents we can confirm the cation.
Group Cations Specific precipitating agents
I Hg+, Pb2+, Ag+ Dilute HCl
II
Bi3+, Cu2+, Hg2+, Cd2+, Pb2+, Sn2+, Sn4+,
Sb3+, Sb5+, As3+, As5+
H2S
III Fe2+, Fe3+, Al3+, Cr3+, Zn2+, Ni2+, Co2+, Mn2+ NH4Cl + excess NH4OH(NaOH + NH4OH)
IV Ca2+, Ba2+, Sr2+ (NH4)2CO3(& Na2CO3)
V Na+, K+, Mg2+, NH4
+ -
The whole process of group identification can be shown using the following flow-chart.
Md.
Imran
Nur
Manik

The cations of group I are separated when dilute HCl is added because of the formation of
insoluble chloride salts. Thus, to identify whether the cation belongs to group I or not, one
should add dilute HCl. If precipitate is formed, then the specific cation must be identified.
Ag+ + Cl–AgCl(s)
Pb2+ + 2Cl– PbCl2
For the confirmation of the specific cation of group I following process should be utilized.
Confirmation
test
Description Reactions
Ag+ test
When NH3 solution is added to
silver chloride, the white
precipitate dissolves.
Ag++ NH4OH⇌[Ag(NH3)2]+
Pb2+ test
Potassium chromate is added to
the stock solution.
A bright yellow precipitate
confirms Pb2+ ion.
Pb2+(aq) + K2CrO4(aq) →PbCrO4(s)
If no precipitate is formed when dilute HCl is added to the stock solution, then group I
cations are not present. Then we have to add H2S which will form insoluble sulfide salts of
group II cations. H2S is not directly produced, rather thioacetamide is added which will
produce H2S in solution.
Hg2+ + H2S HgS (black) + 2H+ + 2Cl–
Cu2+ + H2S CuS (black) + 2H+ + 2Cl–
If precipitates are formed upon addition of thioacetamide, the next step is to confirm the
cation.
Confirmation
test
Description Reaction
Hg2+ test
When HNO3 is added, HgS doesn’t
dissolve, but sulfides of other cations
dissolve.
Then HCl is added (aqua regia), which
will cause formation of soluble HgCl2
(mercuric chloride) salt.
Addition of SnCl2 will cause formation of
Hg2Cl2 and elemental Hg both which
form precipitates.
HgS +HNO3 X
HgS + HNO3 + 6Cl–+ 8H+ 
3HgCl2 + 2NO + 3S + 4H2O
Hg2Cl2 + Sn2+ 
Hg + Hg2Cl2 + Sn4+
Cu2+ test
When Sodium hydroxide is added to a
solution of cupric (Cu2+) ions, blue
gelatinous precipitate will form.
When aqueous ammonia is added to a
solution of cupric (Cu2+) ions, blue
precipitate will form. Excess addition of
ammonia will dissolve the blue
precipitate forming a deep blue color.
Cu2+ + NH4OH Cu(OH)2
(blue PPT)
Cu2+ + NH4OH Cu(OH)2
(blue PPT)
Cu(OH)2 + NH4OH 
[Cu(NH3)4]2+ (blue sol.)
Md.
Imran
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Manik

4. Test tubes
5. Pipette (5mL)
6. Water bathand/or ice bath
A. For group I cations
a. Dilute hydrochloric acid (6M)
b. Ammonia solution (9M)
c. Potassium chromate (1M)
B. For group II cations
a. Ferrous sulfide (FeS)
b. Concentrated sulfuricacid
c. Nitric acid (6M)
d. Stannous chloride (0.1M)
e. Concentrated Ammonia solution (9M)
f. Dilute Ammonia solution (2M)
g. Dilute Sodium hydroxide solution (2M)
5. Procedure
5.1 Test for group I cations
CAUTION: Take special care when handling hydrochloric acid, it is extremely
3. Check to see if precipitate is formed.
4. If precipitate is formed, go for confirmation tests.
5. If precipitate is not formed, go for test of group II cations.
5.1.1 Confirmation test of Ag+
1. Take the solution containing the precipitate.
2. Add 2-3mL of ammonia solution. If the precipitate is dissolved, then Ag+ is
confirmed.
5.1.2 Confirmation test of Pb2+
1. Take 2mL of the stock solution in a test tube.
2. Add 0.5mL of 1M potassium chromate solution. If precipitate starts to form, add
more 1M potassium chromate (up to 2mL).
3. Bright yellow precipitate confirms Pb2+ ions.
5.2 Test for group II cations
7. From 5.1, take the solution and add H2S from the apparatus.
8. Check to see if any precipitate is formed. If black precipitate is formed, first go for
Hg2+ or Cu2+ confirmation test.
Md.
Imran
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Manik

5.2.1 Confirmation test of Hg2+
1. First separate the black precipitate from the solution by filtration.
2. Take the precipitate in another test tube and add 1mL distilled water.
3. Then add 1mL 6M Nitric acid & Shake vigorously.
4. If precipitate doesn’t dissolve, it is indicative of the presence of Hg2+.
5. Add 1mL 6M HCl and 1mL 6M HNO3 to the test tube. Heat in a boiling water bath.
6. Cool the solution in an ice bath.
7. Add 0.5mL of 0.1M SnCl2 drop wise.
8. Grey to black precipitates confirms the presence of Hg2+.
5.2.2 Confirmation test of Cu2+
2. Add 0.5 mL dilute NaOH solution drop wise.
3. Check to see if light blue gelatinous precipitate is formed.
4. If precipitate is observed, then add more NaOH solution. Precipitate insoluble in
excess alkali.
5. Again take 2mL of the stock solution in a test tube
6. Add 0.5 mL dilute ammonia solution drop wise.
7. Check to see if light blue precipitate is formed.
8. If precipitate is observed, then add more ammonia solution. A deep blue colored
solution will be formed. This confirms the presence of Cu2+.
6. Inference
Group
test
Confirmation
test
Group I
-
Hg+ test
Ag+ test
Pb2+ test
Group II
-
Hg2+ test
Cu2+ test
7. Result
8. Precautions
Specimen: Writing inference
Confirmatory test for Group II cations
2ml stock solution was taken in a test tube and
2M NaOH solution was added to it.
Blue gelatinous PPTwas formed.
Reaction: Cu2+
(aq)+2OH–
(aq)Cu(OH)2(s)
Blue PPT
Cu2+
Present
Then excess 2M NaOH solution was added to it. The Precipitate was insoluble in excess NaOH.
Again, 2ml stock solution was again taken in a
test tube and ammonia solution was added to it.
Blue gelatinous PPT formed.
Reaction:
Cu2+
(aq)+2NH3(aq)+2H2OCu(OH)2(s)+
2NH4
+
(aq)
Blue gelatinous PPT
Cu2+
Confirmed
Afterwards, excess ammonia solution was added
to it.
Precipitate was soluble in excess 2M NH4OH.
Excess aq. NH3
Cu(OH)2 (s)+ 4NH3(aq) 
[Cu(NH3)4]2+
(aq)+ 2OH–
(aq)
Tetraamminecopper(II) ion
Md.
Imran
Nur
Manik

Experiment No. 02-C
Qualitative analysis (identification) of group III.
2. Principle
nature) are classified into five groups. Cations of each group is precipitated a common
reagent. So, by step-wise addition of those reagents, we can first identify which group the
cation belongs to. Then by using specific reagents we can confirm the cation.
The common inorganic cations can be classified into five groups based on solubility
characteristics. Cations of each class are precipitated by a specific reagent.
II Bi3+, Cu2+, Hg2+, Cd2+, Pb2+, Sn2+, Sn4+,
Sb3+, Sb5+, As3+, As5+
H2S
III Fe2+, Fe3+, Al3+, Cr3+, Zn2+, Ni2+, Co2+, Mn2+ NH4Cl + excess NH4OH(NaOH + NH4OH)
IV Ca2+, Ba2+, Sr2+ (NH4)2CO3(& Na2CO3)
+ -
Cations of group III are not precipitated by dilute HCl or H2S, but they can be precipitated
from a salt solution by the addition of NH4Cl in the presence of excess NH4OH.
With this reagent, hydroxide or sulphide salts of cation will be precipitated. If precipitate
is formed, then confirmation tests should be performed to identify specific cation.
Confirmation test Description Reactions
Fe2+ test
If the precipitate from the above reaction is
greenish, then it may be ferrous.
If dilute sodium hydroxide is added to a solution
containing ferrous ions (Fe2+), a green gelatinous
precipitate of iron (II) hydroxide will form.
Excess addition of sodium hydroxide will not
dissolve the precipitate.
When aqueous ammonia (dil. /2M) is added to a
solution of ferrous(Fe2+) ions, a green gelatinous
precipitate will form.
Excess addition of ammonia will not dissolve the
precipitate.
To confirm, potassium ferricyanide is added to
the stock solution, a deep blue precipitate is
obtained.
Fe2+(aq)+2OH–(aq)
Fe(OH)2(s)
Green precipitate
Fe2+(aq)+2NH3(aq)
Fe(OH)2(s) +2NH4
+
(aq)
Green precipitate
Fe2+ + K3[Fe(CN)6] 
KF[Fe(CN)6] (blue PPT)
Md.
Imran
Nur
Manik

Fe3+ test
If the precipitate from the above reaction is
brownish, then it may be ferric.
If dilute sodium hydroxide is added to a solution
containing ferric ions (Fe3+), a brownish red
gelatinous precipitate of iron (III) hydroxide will
form.
Excess addition of sodium hydroxide will not
dissolve the precipitate.
When aqueous ammonia (dil. /2M) is added to a
solution of ferric (Fe3+) ions, a brownish red
Excess addition of ammonia will not dissolve the
precipitate.
To confirm, potassium ferricyanide is added to
the stock solution, a red (greenish) precipitate is
obtained.
In another test, addition of potassium
thiocyanate to stock solution will produce blood
red solution.
Fe3+(aq)+3OH–(aq)
Fe(OH)3(s)
Reddish brown precipitate
Fe3+(aq)+3NH3(aq)
Fe(OH)3(s) +3NH4
+
(aq)
Reddish brown precipitate
Fe3+ + K3[Fe(CN)6] 
F[Fe(CN)6] (red PPT.)
Fe3+ + KCNS + H2O 
[Fe(H2O)5(CNS)]2+ + K+
Zn2+ test
When dilute sodium hydroxide is added to a
solution containing zinc ions (Zn2+), a
gelatinous white precipitate is formed.
Addition of concentrated sodium hydroxide
(excess dil. NaOH) produces a soluble complex
resulting in a clear solution.
When ammonia (dil./2M) is added to a solution
of zinc (Zn2+) ions, white gelatinous precipitate
will form.
Excess addition of ammonia will dissolve the
precipitate forming a water soluble colourless
tetraaminezinc ion.
Zn2++ 2NaOH
Na+ + Zn(OH)2(white PPT.)
Zn(OH)2 + 2NaOH 
Na2[Zn(OH)4](SodiumZincate.)
Zn2+(aq)+2NH3(aq)+2H2OZn
(OH)2(s)+ 2NH4
+(aq)
White gelatinous PPT
Zn (OH)2 (s)+ 4NH3(aq) 
[Zn (NH3)4]2+ (aq)+ 2OH–(aq)
Tetraamminezinc(II) ion
Al3+ test
When dilute sodium hydroxide is added to a
solution containing aluminium ions (Al3+), a
white gelatinous precipitate is formed.
Addition of concentrated sodium hydroxide
(excess dil. NaOH) produces a soluble complex
resulting in a clear solution.
When aqueous ammonia (dil. /2M) is added to
a solution of aluminium (Al3+) ions, white
Excess addition of ammonia will not dissolve
the precipitate.
Al3++ 3OH–Al(OH)3
(white PPT.)
Al(OH)3 (s)+ OH– (aq)
[Al(OH)4]–(aq)
Tetrahydroxoaluminate ion
Al3+(aq)+3NH3(aq)+3H2OAl(
OH)3(s)+ 3NH4
+(aq)
White gelatinous PPT
Md.
Imran
Nur
Manik

1. Test tubes
2. Pipette (5mL)
3. H2S generating apparatus
1. For group III cations
a. Ammonium chloride
b. Ammonia solution (9M)
c. Ammonia solution (2M)
d. Potassium ferricyanide (K3[Fe(CN)6]) [250 mg in 10 ml]
e. Potassium thiocyanate [250 mg in 10 ml]
f. Sodium hydroxide (2M)
g. Sodium hydroxide (10M)
5. Procedure
5.1 Test for group III cations
4. If no precipitate is formed, add H2S in the test tube. Check again to see if
5. If no precipitate is formed above, add 2mL concentrated NH4OH and 1gm of NH4Cl.
Check to see if precipitate is formed.
6. If precipitate is formed then go for confirmation tests. If no precipitate is formed, go
for ‘Test for group IV cations’.
5.1.1 Confirmation test of Fe2+cation
3. Check to see if light green gelatinous precipitate is formed.
excess alkali.
7. Check to see if green gelatinous precipitate is formed.
8. If precipitate is observed, then add more ammonia solution.
Precipitate insoluble in excess aqueous ammonia.
Md.
Imran
Nur
Manik

To further confirm the presence of Fe2+
1. Take 2ml of the stock the solution in a test tube.
2. Add 2mL potassium ferricyanide(just one drop) solution. Check to see if precipitate
is formed.
1. Light blue precipitate confirms the presence of Fe2+.
5.1.2 Confirmation test of Fe3+ cation
3. Check to see if light brownish red gelatinous precipitate is formed.
excess alkali.
7. Check to see if brownish red gelatinous precipitate is formed.
8. If precipitate is observed, then add more ammonia solution.
Precipitate insoluble in excess aqueous ammonia.
To further confirm the presence of Fe3+
1. Take 2ml of the stock the solution in a test tube.
2. Add 2mL potassium ferricyanide(just one drop) solution. Check to see if precipitate
is formed.
3. Brownish (Green) colour indicates Fe3+.
4. To confirm Fe3+, you can also use potassium thiocyanate.
5. Take 2ml of the stock the solution in a test tube and add 2mL of potassium
thiocyanate(just one drop) solution to stock solution, if the colour change to blood
red then Fe3+ is confirmed.
5.1.3 Confirmation test of Zn2+
1. First add 2M sodium hydroxide drop wise very slowly.
2. Check to see if white precipitate has been formed. If precipitate is formed, add
concentrated NaOH (10M) {excess 2M NaOH}to check if the precipitate dissolves.
3. If the precipitate dissolves, then Zn2+ is confirmed.
4. Again take 2mL of the stock solution in a test tube.
5. Now add ammonia (dil. /2M) drop wise very slowly.
concentrated ammonia (9M) {excess 2M ammonia} to check if the precipitate
dissolves.
7. If the precipitate dissolves, then Zn2+ is further confirmed.
(10dilution may be needed for the appearance and disappearance of PPT)
Md.
Imran
Nur
Manik

5.1.4 Confirmation test of Al3+
2. First add 2M sodium hydroxide drop wise very slowly.
3. Check to see if white gelatinous precipitate has been formed. If precipitate is
formed, add concentrated NaOH (10M) {excess 2M NaOH} to check if the precipitate
dissolves.
4. If the precipitate dissolves, then Al3+ is confirmed.
5. Again take 2mL of the stock solution in a test tube.
6. Now add ammonia (dil. /2M) drop wise very slowly.
concentrated ammonia (9M) {excess 2M ammonia} to check if the precipitate
dissolves.
8. If the precipitate does not dissolves, then Al3+ is further confirmed.
6. Inference
Group
test
Confirmation
test
Group
III
-
Fe2+ test
Fe3+ test
Zn2+ test
Al3+ test
7. Result
8. Precautions
Specimen: Writing inference
Analysis for Group III cations
2ml stock solution was taken in a test
tube and 2M NaOH solution was
added to it.
Green gelatinous PPTwas formed.
Reaction: Fe2+
(aq)+2OH–
(aq)Fe(OH)2(s)
Green jelly like PPT Fe2+
Present
Then excess 2M NaOH solution was
added to it.
Precipitate was insoluble in excess NaOH.
2ml stock solution was again taken in
a test tube and ammonia solution was
added to it.
Green gelatinous PPT formed.
Reaction: Fe2+
(aq)+2NH3(aq)+2H2OFe(OH)2(s)+ 2NH4
+
(aq)
Green gelatinous PPT Fe2+
Present
Afterwards, excess ammonia solution
was added to it.
Precipitate was insoluble in excess aqueous ammonia solution.
Again 2mL of the stock solution was
taken in a test tube and one drop
potassium ferricyanide solution was
added to it.
Light blue precipitate was formed.
Fe2+
+ K3[Fe(CN)6] KF[Fe(CN)6]
(blue PPT)
Fe2+
Confirmed
Md.
Imran
Nur
Manik

Experiment No. 02-D
Qualitative analysis (identification) of group IV & group V cations.
2. Principle
nature) are classified into five groups. Cations of each group is precipitated a common
reagent. So, by step-wise addition of those reagents, we can first identify which group the
cation belongs to. Then by using specific reagents we can confirm the cation.
The common inorganic cations can be classified into five groups based on solubility
characteristics. Cations of each class are precipitated by a specific reagent.
II Bi3+, Cu2+, Hg2+, Cd2+, Pb2+, Sn2+, Sn4+,
Sb3+, Sb5+, As3+, As5+
H2S
III Fe2+, Fe3+, Al3+, Cr3+, Zn2+, Ni2+, Co2+, Mn2+ NH4Cl + excess NH4OH (NaOH + NH4OH)
IV Ca2+, Ba2+, Sr2+ (NH4)2CO3 (& Na2CO3)
+ -
Cations of group IV are not precipitated by dilute HCl or H2S, as well as by the addition of
NH4Cl in the presence of excess NH4OH.
If no precipitate is formed with the addition of NH4OH and NH4Cl to the stock solution,
then (NH4)2CO3 is added to it. If precipitate is formed, then group IV cations are present.
In that case, confirmation tests are carried out as follows:
Confirmation
test
Description Reaction
Ca2+ test
When the sample salt (solid form or solution)
is heated in Bunsen burner, a brick-red flame
confirms presence of Ca2+.
NH4
+ test
If Nessler’s reagent is added to a solution
containing ammonium ions (NH4
+), a brown
When sodium hydroxide is added to a solution
containing ammonium ions (NH4
+), and the
mixture a colourless gas will be produced
which turns moist red litmus paper blue.
NH4
+ + 2[HgI4]2− +
4OH− →HgO·Hg(NH2)I(s)↓
+ 7I− + 3H2O(Yellow or brown)
NH4
+ (aq)+ OH– 
NH3(g) + H2O(l)
Ammonia
Md.
Imran
Nur
Manik

a) Test tubes
b) Pipette (5mL)
c) H2S generating apparatus
d) Platinum wire
1.For group IV cations
a) Ammonium carbonate
b) Conc. hydrochloric acid
2.For group V cations
a) Litmus paper (red)
b) Nessler's reagent [a 0.09 mol/L solution of potassium tetraiodomercurate(II)
(K2[HgI4]) in 2.5 mol/L potassium hydroxide]
5. Procedure
5.1 Test for group IVcations
4. If no precipitate is formed, add H2S in the test tube. Check again to see if
5. If no precipitate is formed above, add 2mL concentrated NH4OH and 1gm of NH4Cl.
Check to see if precipitate is formed.If precipitate is formed then go for confirmation
tests.
6. If no precipitate is formed, then add (NH4)2CO3.If precipitate is formed, then go for
‘Test for group IV cations’.
7. If no precipitate is formed, then go for ‘Test for group V cations’.
5.2 Test for group IVcations
1. From 5.1, take the solution and add 5% ammonium carbonate solution.
2. Check to see if any precipitate is formed. If precipitate is formed,
go for confirmation test.
5.2.1 Confirmation test of Ca2+
1. Take a platinum or nichrome wire and dip it in concentrated hydrochloric acid.
2. Then heat the wire in Bunsen burner until flame is no longer visible.
3. Then take the wire and dip it in the sample salt solution. Conversely, you can dip it
in a solid sample of the salt.
4. Place the wire in the Bunsen burner. Observe the flame colour.
5. Brick-red flame confirms the presence of Ca2+ in the sample.
Md.
Imran
Nur
Manik

5.2.2 Confirmation test of NH4
+
2. Add Nessler's reagent drop wise.
3. Check to see if brown precipitate has been formed. If precipitate is not forming or
disappears as quickly as it forms then add more Nessler’s reagent until the
precipitate forms.
4. Add more Nessler’s reagent to check if the precipitate dissolves.
5. If the precipitate does not dissolve, then NH4
+is confirmed.
For further confirmation
2. Add 3ml NaOH solution to it.
3. Then heat the solution carefully in Bunsen burner until a colourless gas evolves.
4. Place a moist red litmus paper in the mouth of the test tube.
5. Check to see if the red litmus paper turns into blue.
6. If the colourless gas turns the red litmus paper into blue then NH4
+is further
confirmed.
Hold the tube containing the ammonium nitrate solution with a test-tube
holder. Gently warm the tube along its sides using a back-and-fort
motion through a burner flame. Do not allow the solution to boil.
CAUTION: At all times, make sure that the opening of the tube is
pointed away from other people. Hold a moistened piece of red litmus
paper near the mouth of the test tube, as shown in Figure. The test will
be spoiled if the solution contacts the litmus paper. Record the changes
you observe. Fan the vapours coming out of the tube toward your nose
with your hand. Cautiously sniff the vapours. Record your observations.
6. Inference
Group
test
Confirmation
test
Group
IV
-
Ca2+ test
Group
V
-
NH4
+ test
7. Result
8. Precautions
Md.
Imran
Nur
Manik

Qualitative analysis of salts lab manual MANIK

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