CERTIFICATE
OF EXCELLENCE
SYLLABUS
A. Surface Chemistry
(a) Preparation of one lyophilic and one
lyophobic sol Lyophilic sol - starch, egg albumin and gum Lyophobic sol -
aluminium hydroxide, ferric hydroxide, arsenous sulphide.
(b)
Dialysis of sol-prepared in (a) above.
(c)
Study of the role of emulsifying agents in stabilizing the emulsion of
different oils.
B. Chemical Kinetics
(a) Effect of concentration and temperature on
the rate of reaction between Sodium Thiosulphate and Hydrochloric acid.
(b) Study of reaction rates of any one of the
following:
(i) Reaction of Iodide ion with Hydrogen
Peroxide at room temperature using different concentration of Iodide ions.
(ii)
Reaction between Potassium Iodate, (KIO3) and Sodium Sulphite: (Na2SO3) using
starch solution as indicator (clock reaction).
C. Thermochemistry Any one of the following
experiments
i) Enthalpy of dissolution of Copper Sulphate
or Potassium Nitrate.
ii) Enthalpy of neutralization of strong acid
(HCI) and strong base (NaOH).
iii)
Determination of enthaply change during interaction (Hydrogen bond formation)
between Acetone and Chloroform.
D.
Electrochemistry
i) Variation
of cell potential in Zn/Zn2+|| Cu2+/Cu with change in concentration of
electrolytes (CuSO4 or ZnSO4) at room temperature.
E.
Chromatography
i)
Separation of pigments from extracts of leaves and flowers by paper
chromatography and determination of Rf values. ii) Separation of constituents
present in an inorganic mixture containing two cations only (constituents
having large difference in Rf values to be provided).
F. Preparation of Inorganic Compounds
Preparation of double salt of Ferrous Ammonium Sulphate or Potash Alum.
Preparation of Potassium Ferric Oxalate.
G.
Preparation of Organic Compounds Preparation of any one of the following
compounds i) Acetanilide ii) Di -benzalAcetone iii) p-Nitroacetanilide iv)
Aniline yellow or 2 - Naphthol Anilinedye. H. Tests for the functional groups
present in organic compounds: Unsaturation, alcoholic, phenolic, aldehydic,
ketonic, carboxylic and amino (Primary) groups.
I. Characteristic
tests of carbohydrates, fats and proteins in pure samples and their detection
in given foodstuffs.
J. Determination of concentration/ molarity of
KMnO4 solution by titrating it against a standard solution of:
i) Oxalic acid, ii) Ferrous Ammonium Sulphate (Students will
be required to prepare standard solutions by weighing themselves).
K. Qualitative
analysis Determination of one cation and one anion in a given salt. Cation
: Pb2+, Cu2+ As3+, Aℓ3+, Fe3+, Mn2+, Zn2+, Cu2+, Ni2+, Ca2+, Sr2+, Ba2+, Mg2+,
NH4 + Anions: (CO3) 2- , S2- , (SO3) 2- , (NO2) - , (SO4) 2- , Cℓ - , Br- , I-
, PO3- 4, (C2O4) 2- , CH3COO- ,NO3 –
PROJECT
Scientific investigations involving laboratory testing and
collecting information from other sources A few suggested Projects.
• Study of the presence of oxalate ions in guava fruit at
different stages of ripening.
• Study of quantity of casein present in different samples of
milk.
• Preparation of soybean milk and its comparison with the
natural milk with respect to curd formation, effect of temperature, etc.
• Study of the effect of Potassium Bisulphate as food
preservative under various conditions (temperature, concentration, time, etc.)
• Study of digestion
of starch by salivary amylase and effect of pH and temperature on it.
• Comparative study of the rate of fermentation of following
materials: wheat flour, gram flour, potato juice, carrot juice, etc.
• Extraction of essential oils present in Saunf (aniseed),
Ajwain (carum), Illaichi (cardamom).
• Study of common food adulterants in fat, oil, butter,
sugar, turmeric power, chilli powder and pepper. Note: Any other investigatory
project, which involves about 10 periods of work, can be chosen with the
approval of the teacher.
INDEX
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1. Safety goggles (department
approved) must be worn in the lab at all times.
2. Never eat or drink in the lab.
Food may pick up toxic chemicals.
3. Never inhale fumes or vapors.
4. Never taste any chemical.
5. Never perform an unauthorized
experiment and never work in the lab without an instructor in charge.
6. Never remove anything (chemicals,
glassware, etc.) from the lab. It is illegal!
7. Label all containers to identify their
contents.
8. Never put anything back into a
reagent bottle.
9. Leave chemicals in their proper
place.
10.Avoid touching hot objects.
11.Rinse spills off skin immediately.
12.Clean up broken glassware
immediately
13.Properly dispose of waste chemicals
14.Notify your instructor immediately
of all accidents.
15. Learn to locate and operate (if
applicable), the safety shower, fire extinguisher, eye-wash fountain, fire
blanket, and fire exit.
------------------------------------------------------------------------------------
CHEMISTRY PRACTICAL
VIKASLODHI
MSC. B.Ed
A. VOLUMIC ESTIMATIONS
1. Volumetric Analysis: A quantitative
analytical method used to determine the concentration of a solute in a solution
by measuring the volume of a standard solution required to react completely
with the analyte.
2. Titration: A process in which a
solution of known concentration (titrant) is gradually added to a solution of
unknown concentration (analyte) until the reaction reaches completion, often
indicated by a color change.
3. Titrant: The solution of known
concentration used in a titration. It is added to the analyte until the
endpoint is reached.
4. Analyte: The substance whose
concentration is being determined in a titration. It reacts with the titrant.
5. Standard Solution: A solution of known
concentration used as a reference in titrations. It is prepared by dissolving a
known amount of solute in a specific volume of solvent.
6. Equivalence Point: The point in a titration at which
the amount of titrant added is chemically equivalent to the amount of analyte
present in the sample.
7. Endpoint: The point in a titration at which a
sudden change in a physical property (such as color) indicates that the
titration is complete. It is used to approximate the equivalence point.
8. Indicator: A substance that changes color at
or near the equivalence point of a titration, helping to visually identify the
endpoint.
9. Primary Standard: A highly pure chemical substance
used to prepare standard solutions for titrations. It must have a known and
stable composition, be readily available, and react completely and rapidly with
the analyte.
10. Secondary Standard: A solution whose
concentration has been determined by titration with a primary standard. It is
used in subsequent titrations.
11. Molarity (M): A unit of concentration,
defined as the number of moles of solute per liter of solution. It is commonly
used in volumetric analysis to express the concentration of the titrant and
analyte.
12. Burette: A graduated glass tube with a
tap at one end, used to deliver known volumes of a liquid, especially in
titrations.
13. Pipette: A laboratory tool used to measure and transfer a specific
volume of liquid from one container to another.
14. Meniscus: The curved surface of a liquid in
a container. The bottom of the meniscus is used as the reference point for
reading volumes in volumetric analysis.
15. Aliquot: A measured sub-volume of a sample.
It is often used in titrations to represent a portion of the total sample being
analyzed.
16. Back Titration: A technique where an excess of a
standard reagent is added to a solution, and the excess is then titrated with
another reagent. This method is useful for analyzing substances that react
slowly or incompletely with the titrant.
17. Complexometric Titration: A type of
titration used to determine the concentration of metal ions in solution using a
chelating agent, such as EDTA, which forms a complex with the metal ions.
18. **Redox Titration**: A titration based on a redox
reaction between the analyte and the titrant. It involves the transfer of
electrons between the reacting species.
19. **Acid-Base Titration**: A titration involving the reaction
between an acid and a base. The equivalence point is often determined using a
pH indicator or a pH meter.
20. **Gravimetric Analysis**: A method where the analyte is
converted into a solid product, which is then weighed. This technique can be
used to determine the concentration of the analyte in the original solution.
21. **Potentiometric Titration**: A titration in which the potential
difference (voltage) between two electrodes is measured to determine the
endpoint of the titration.
22. **Standardization**: The process of determining the
exact concentration of a solution. This is typically done by titrating the
solution against a primary standard.
23. **Buffer Solution**: A solution that resists changes in
pH when small amounts of an acid or base are added. It is often used in
titrations to maintain a stable pH environment.
24. **Dilution**: The process of reducing the
concentration of a solute in a solution, usually by adding more solvent.
25. **Volumetric Flask**: A type of laboratory flask
calibrated to contain a precise volume at a particular temperature. It is used
for preparing standard solutions.
26. **Calibration**: The process of adjusting and
verifying the accuracy of a measurement instrument, such as a burette or
pipette.
27. **Titre**: The volume of titrant required to
reach the endpoint of a titration.
28. **Titration Curve**: A graph showing the change in a
physical property (such as pH) as a function of the volume of titrant added. It
is used to analyze the progress of a titration and identify the equivalence
point.
29. **Hydrolysis**: A chemical reaction involving
water, often used in titrations of salts where the reaction with water affects
the pH of the solution.
30. **Molar Mass**: The mass of one mole of a
substance, usually expressed in grams per mole. It is used in calculations to
determine the amount of a substance in a sample.
31. **Stoichiometry**: The calculation of reactants and
products in chemical reactions. It is essential in volumetric analysis for
determining the correct proportions of reactants.
32. **Equilibrium Constant (K_eq)**: A number that expresses the ratio
of the concentration of products to reactants at equilibrium for a reversible
chemical reaction. It is used in titrations involving weak acids and bases to
calculate the extent of the reaction.
33. **Neutralization**: A reaction between an acid and a
base to form water and a salt. It is the basis for many acid-base titrations.
34. **Oxidation Number**: A number assigned to an element in a
chemical compound that represents the number of electrons lost or gained by an
atom of that element in the compound. It is used in redox titrations to balance
redox equations.
35. **Endpoint Detection**: Various methods to detect the
endpoint of a titration, including visual indicators, pH meters, and
potentiometric measurements.
EXPERIMENT
1.1
Determination of
Concentration/Molarity of KMnO4 using Oxalic Acid
**Aim:**
To determine the
concentration/molarity of potassium permanganate (KMnO4) solution by titrating
it against a 0.1 M standard solution of oxalic acid.
**Theory:**
- KMnO4 is a strong
oxidizing agent in an acidic medium.
- In the acidic
medium, KMnO4 reacts with oxalic acid, which acts as a reducing agent.
- The reaction involves
the reduction of MnO4- to Mn2+ and the oxidation of C2O42- to CO2.
**Chemical
Reaction:**
\[ 2 \text{KMnO}_4 +
3 \text{H}_2\text{SO}_4 + 5 \text{H}_2\text{C}_2\text{O}_4 \rightarrow
K_2\text{SO}_4 + 2 \text{MnSO}_4 + 10 \text{CO}_2 + 8 \text{H}_2\text{O} \]
**Materials
Required:**
- Burette, conical
flask, pipette, measuring flask
- 0.1 M oxalic acid
solution
- KMnO4 solution
- 1.0 M sulphuric
acid (H2SO4)
- Burner and white
glazed tile
**Procedure:*
1. **Preparation of
Oxalic Acid Solution:**
-
Prepare a 0.1 M oxalic acid solution.
2. **Titration:**
- Fill a burette with KMnO4 solution.
- Take 10 mL of 0.1 M oxalic acid in a
conical flask and add 5 mL of 1.0 M H2SO4.
- Heat the oxalic acid solution to 50-60°C.
- Titrate with KMnO4 solution from the
burette until a permanent light pink color appears.
- Record the volume of KMnO4 used.
- Repeat the titration to obtain three
consistent readings.
**Observation
Table:**
| S.No. | Volume of
Oxalic Acid (mL) | Volume of KMnO4 (mL) |
|-------|-----------------------------|-----------------------|
| 1 | 10 | |
| 2 | 10 | |
| 3 | 10 | |
**Result:**
- Average volume of
KMnO4 used: \[ \text{(V1 + V2 + V3) / 3} \]
- Molarity of KMnO4:
\[ \text{M2} = \frac{2 \times 0.1 \times 10}{5 \times \text{Average Volume of
KMnO4}} \]
EXPERIMENT
1.2
Experiment 1.2:
Determination of Concentration/Molarity of KMnO4 using Ferrous Ammonium
Sulphate
**Aim:**
To determine the
concentration/molarity of potassium permanganate (KMnO4) solution by titrating
it against a standard solution of ferrous ammonium sulphate
(FeSO4·(NH4)2SO4·6H2O).
**Theory:**
- Ferrous ammonium
sulphate acts as a reducing agent.
- In the titration,
KMnO4 is reduced while Fe2+ is oxidized to Fe3+.
**Chemical
Reaction:**
\[ 2 \text{KMnO}_4 +
8 \text{H}_2\text{SO}_4 + 10 \text{FeSO}_4\cdot(\text{NH}_4)_2\text{SO}_4\cdot6\text{H}_2\text{O}
\rightarrow K_2\text{SO}_4 + 2 \text{MnSO}_4 + 5 \text{Fe}_2(\text{SO}_4)_3 +
10 (\text{NH}_4)_2\text{SO}_4 + 68 \text{H}_2\text{O} \]
**Materials
Required:**
- Burette, conical
flask, pipette, measuring flask
- 0.05 M ferrous
ammonium sulphate solution
- KMnO4 solution
- 1.0 M sulphuric
acid (H2SO4)
- White glazed tile
**Procedure:**
1. **Preparation of
Ferrous Ammonium Sulphate Solution:**
- Weigh 4.9 g of ferrous ammonium sulphate
and dissolve in water in a 250 mL flask.
- Add dilute H2SO4 dropwise to clear the
solution and make up to the mark with distilled water.
2. **Titration:**
- Fill a burette with KMnO4 solution.
- Take 10 mL of 0.05 M ferrous ammonium
sulphate in a conical flask and add 5 mL of 1.0 M H2SO4.
- Titrate with KMnO4 solution from the
burette until a permanent light pink color appears.
- Record the volume of KMnO4 used.
- Repeat the titration to obtain three
consistent readings.
**Observation
Table:**
| S.No. | Volume of
Ferrous Ammonium Sulphate (mL) | Volume of KMnO4 (mL) |
|-------|------------------------------------------|-----------------------|
| 1 | 10 | |
| 2 | 10 | |
| 3 | 10 | |
**Result:**
- Average volume of
KMnO4 used: \[ \text{(V1 + V2 + V3) / 3} \]
- Molarity of KMnO4:
\[ \text{M2} = \frac{0.05 \times 10}{5 \times \text{Average Volume of KMnO4}}
\]
Precautions:
-
Make sure all glassware is clean.
B. Surface Chemistry
EXPERIMENT
2.1
Aim: (a) To prepare one lyophilic sol
(starch, egg albumin, or gum) and one lyophobic sol (aluminum hydroxide, ferric
hydroxide, or arsenious sulphide).
Apparatus and
Chemicals:
- Beakers
- Test
tubes
- Glass
rod
- Bunsen
burner
- Starch
- Egg
albumin
- Gum
- Aluminium
sulfate
- Ferric
chloride
- Arsenous
oxide
- Dilute
hydrochloric acid (HCl)
- Distilled
water
Theory:
-Lyophilic sols:Colloidal
solutions where the dispersed particles attract the solvent.
Examples: starch, egg albumin,
gum.
Lyophobic sols: Colloidal solutions where the dispersed particles
do not attract the solvent. Examples: aluminium hydroxide, ferric hydroxide,
arsenous sulphide.
Procedure:
Part A: Preparation of Lyophilic
Sol
Starch Sol
Preparation:
1. Make
a Starch Paste: - Mix a small amount of starch powder (about 1 g) with a little
cold distilled water to form a paste.
2. Dissolve
the Starch: - Boil 100 mL of distilled water in a beaker. Add the starch paste
to the boiling water while stirring continuously. Continue boiling until a
clear solution forms.
3. Cool
the Solution: - Let the solution
cool down. This is your lyophilic sol of starch.
Egg Albumin Sol
Preparation:
1. Dissolve the Albumin:
-
Mix the white part of an egg with 100 mL of distilled
water.
-
Stir well to make a uniform mixture.
2. Filter the Solution:
-
Filter the mixture to remove any undissolved particles.
-
The filtered solution is your lyophilic sol of egg
albumin.
Gum Sol Preparation:
1. Dissolve the Gum:
-
Add 1 g of gum to 100 mL of distilled water.
-
Stir well until the gum completely dissolves.
-
The resulting solution is your lyophilic sol of gum.
Part B: Preparation of Lyophobic Sol
Aluminium Hydroxide Sol Preparation:
1. Prepare the
Reaction:
- Pour 50 mL of 0.1 M aluminium
sulfate solution into a beaker.
2. Form the Sol:
-
Add a few drops of dilute hydrochloric acid while
stirring.
-
Gradually add ammonium hydroxide solution until the
precipitate just dissolves to form a colloidal sol of aluminium hydroxide.
Ferric Hydroxide Sol
Preparation:
1. Prepare the
Reaction:
- Pour 50 mL of 0.1 M ferric
chloride solution into a beaker.
2. Form the Sol:
-
Boil the solution, then add a few drops of dilute
hydrochloric acid.
-
Add ammonium hydroxide solution drop by drop until a
reddish-brown precipitate forms and then just dissolves to form a colloidal sol
of ferric hydroxide.
Arsenous Sulphide
Sol Preparation:
1. Prepare the
Reaction:
- Pour 50 mL of distilled water
into a beaker.
2. Form the Sol:
-
Add 0.1 g of arsenous oxide and dissolve it completely
by adding a few drops of dilute hydrochloric acid.
-
Pass hydrogen sulphide gas through the solution until a
yellow precipitate forms.
-
Filter the precipitate and dissolve it in hot distilled
water to form a colloidal sol.
Observations:
-
Lyophilic Sols:
-
Starch sol: Clear solution.
-
Egg albumin sol: Homogeneous mixture.
-
Gum sol: Viscous solution.
-
Lyophobic Sols:
-
Aluminium hydroxide sol: Translucent colloidal
solution.
-
Ferric hydroxide sol: Reddish-brown colloidal solution.
-
Arsenous sulphide sol: Yellow colloidal solution.
Result:
-
Successfully prepared a lyophilic sol of __________ and
a lyophobic sol of __________.
Precautions:
-
Make sure all glassware is clean.
-
Add reagents slowly and stir continuously to avoid
lumps.
-
Handle chemicals like hydrochloric acid and ammonium
hydroxide carefully.
Viva Questions:
1. What
is the difference between lyophilic and lyophobic sols?
2. Why
is continuous stirring important in preparing colloidal solutions?
3. How
can you distinguish between a true solution and a colloidal solution?
4.
What role does ammonium hydroxide play in preparing
aluminium hydroxide sol?
EXPERIMENT
2.2
B.) To perform dialysis of the sol prepared in (a).
Apparatus and
Chemicals:
- Distilled
water
-Lyophobic Sols:
- Lyophilic
Sols:
- Dialysis
membrane (or parchment paper)
Theory:
- Dialysis: A process to remove
impurities (such as ions or small molecules) from colloidal solutions by
diffusion through a semi-permeable membrane.
Procedure:
1. Setup:
- Take a
dialysis membrane or parchment paper and soak it in distilled water for a few
minutes.
2. Dialysis Process:
-
Pour the prepared colloidal sol into the dialysis
membrane.
-
Immerse the filled dialysis membrane in a beaker
containing distilled water.
-
Allow the setup to stand for a few hours or overnight.
3.
Change the Water: - Replace the distilled water in the
beaker periodically to ensure effective removal of impurities.
4.
Completion: - After sufficient time, check if the
impurities have been removed from the sol by testing the water outside the
membrane.
Observations:
- Dialysis:
- Clearer
sol with reduced impurities.
Result:
- Dialysis
effectively removed impurities from the prepared sols.
Precautions:
- Make
sure all glassware is clean.
- Add
reagents slowly and stir continuously to avoid lumps.
- Handle
chemicals like hydrochloric acid and ammonium hydroxide carefully.
- Ensure
the dialysis membrane is properly soaked and handled gently.
Viva Questions:
1. What
is the difference between lyophilic and lyophobic sols?
2. Why
is continuous stirring important in preparing colloidal solutions?
3. How
can you distinguish between a true solution and a colloidal solution?
4. What
is the purpose of dialysis in colloidal chemistry?
5. What
role does ammonium hydroxide play in preparing aluminium hydroxide sol?
EXPERIMENT
2.3
Aim: (c) To study the role of emulsifying agents
in stabilizing the emulsion of different oils.
Apparatus and
Chemicals:
- Beakers
- Test
tubes
- Glass
rod
- Bunsen
burner
- Starch
- Egg
albumin
- Gum
- Aluminium
sulfate
- Ferric
chloride
- Arsenous
oxide
- Dilute
hydrochloric acid (HCl)
- Ammonium
hydroxide (NH4OH)
- Distilled
water
- Dialysis
membrane (or parchment paper)
- Various
oils (e.g., olive oil, castor oil, coconut oil)
- Emulsifying
agents (e.g., soap, egg yolk, lecithin)
Theory:
- Emulsion: A mixture of two immiscible
liquids where one liquid is dispersed in the other in the form of small
droplets.
- Emulsifying
agents: Substances that stabilize emulsions by reducing the surface tension between
the two immiscible liquids.
Procedure:
Part D: Study of
Emulsifying Agents
1. Prepare Emulsions:
- Take three
test tubes and add 5 mL of oil (e.g., olive oil, castor oil, or coconut oil) to
each.
2. Add Emulsifying Agents:
- Add a small
amount of different emulsifying agents to each test tube (e.g., a few drops of
soap solution, egg yolk, or lecithin).
3. Mix and Observe:
- Shake each
test tube vigorously to form an emulsion.
- Let the
test tubes stand and observe the stability of the emulsions over time.
Observations:
- Lyophilic
Sols:
- Starch sol:
Clear solution.
- Egg albumin
sol: Homogeneous mixture.
- Gum sol:
Viscous solution.
- Lyophobic
Sols:
- Aluminium
hydroxide sol: Translucent colloidal solution.
- Ferric
hydroxide sol: Reddish-brown colloidal solution.
- Arsenous
sulphide sol: Yellow colloidal solution.
- Dialysis:
- Clearer sol
with reduced impurities.
- Emulsions:
- Stability
of emulsions with different oils and emulsifying agents.
Result:
- Emulsifying
agents significantly improve the stability of emulsions.
Precautions:
- Make sure
all glassware is clean.
- Shake
the emulsions well to ensure proper mixing.
Viva Questions:
1. What
is the difference between lyophilic and lyophobic sols?
2. Why
is continuous stirring important in preparing colloidal solutions?
3. How
can you distinguish between a true solution and a colloidal solution?
4. What
is the purpose of dialysis in colloidal chemistry?
5. What
role does ammonium hydroxide play in preparing aluminium hydroxide sol?
6.
How do emulsifying agents stabilize emulsions?
C. CHEMICAL KINETICS
EXPERIMENT
3
Aim:
(a)
To study the effect of concentration and temperature on
the rate of reaction between sodium thiosulphate and hydrochloric acid.
(b)
To study the reaction rates of one of the following
reactions:
●
(i) Reaction of iodide ion with hydrogen
peroxide at room temperature using different concentrations of iodide ions.
●
(ii) Reaction between potassium iodate (KIO3)
and sodium sulphite (Na2SO3) using starch solution as an indicator (clock
reaction).
Apparatus and
Chemicals:
●
Beakers
●
Test tubes
●
Measuring cylinders
●
Stopwatch
●
Thermometer
●
Sodium thiosulphate (Na2S2O3)
●
Hydrochloric acid (HCl)
●
Distilled water
●
Hydrogen peroxide (H2O2)
●
Potassium iodide (KI)
●
Potassium iodate (KIO3)
●
Sodium sulphite (Na2SO3)
●
Starch solution
Theory:
●
Chemical
kinetics studies the rate of chemical reactions and the factors affecting
them, such as concentration and temperature.
●
Rate of
reaction can be measured by observing the change in concentration of
reactants or products over time.
Procedure:
Part A: Effect of Concentration and Temperature on Reaction Rate
Reaction between
Sodium Thiosulphate and Hydrochloric Acid:
Na2S2O3(aq)+2HCl(aq)→2NaCl(aq)+SO2(g)+S(s)+H2O(l)\text{Na}_2\text{S}_2\text{O}_3
(aq) + 2\text{HCl} (aq) \rightarrow
2\text{NaCl} (aq) + \text{SO}_2 (g) + \text{S} (s) + \text{H}_2\text{O}
(l)Na2S2 O3
( aq)+2HCl(aq)→2NaCl(aq)+SO2(
g)+S(s)+H2O(l)
Effect of Concentration:
1.
Prepare
Solutions:
○
Prepare different concentrations of sodium
thiosulphate by diluting with
distilled water (e.g., 0.1 M, 0.2 M, 0.3 M).
2.
Mix and Observe:
○
In a beaker, add a fixed volume of hydrochloric
acid to each concentration of sodium thiosulphate.
○ Start the stopwatch as soon as the acid is added.
○ Record the time taken for the solution
to turn cloudy due to the formation of sulphur.
Effect of
Temperature:
1.
Prepare a
Solution:
○
Use a fixed concentration of sodium
thiosulphate.
2.
Vary
Temperature:
○
Heat the solution to different temperatures
(e.g., 25°C, 35°C, 45°C) using a water bath.
3.
Mix and Observe:
○
Add a fixed volume of hydrochloric acid to the
heated solution.
○ Start the stopwatch as soon as the acid is added.
○ Record the time taken for the solution to turn cloudy at each
temperature.
Part B: Study of Reaction Rates
Option (i): Reaction
of Iodide Ion with Hydrogen Peroxide:
2I−(aq)+H2O2(aq)+2H+(aq)→I2(aq)+2H2O(l)2\text{I}^-
(aq) + \text{H}_2\text{O}_2 (aq) +
2\text{H}^+ (aq) \rightarrow \text{I}_2 (aq) +
2\text{H}_2\text{O}
(l)2I−(aq)+H2O2
( aq)+2H+(aq)→I2(
aq)+2H2O(l)
1.
Prepare
Solutions:
○
Prepare different concentrations of potassium
iodide (e.g., 0.1 M, 0.2 M, 0.3 M).
○ Prepare a fixed concentration of hydrogen peroxide solution.
2.
Mix and Observe:
○
In a test tube, mix a fixed volume of hydrogen
peroxide with each concentration of potassium iodide.
○ Add a small amount of hydrochloric acid to provide H+ ions.
○ Start the stopwatch and record the time
taken for the solution to change color (indicating the formation of iodine).
Option (ii): Clock
Reaction (Potassium Iodate and Sodium Sulphite):
KIO3(aq)+3Na2SO3(aq)→KI(aq)+3Na2SO4(aq)\text{KIO}_3
(aq) + 3\text{Na}_2\text{SO}_3
(aq) \rightarrow \text{KI} (aq) + 3\text{Na}_2\text{SO}_4
(aq)KIO3(
aq)+3Na2SO3 (
aq)→KI(aq)+3Na2SO4 (
aq)
1.
Prepare
Solutions:
○
Prepare a fixed concentration of potassium
iodate and sodium sulphite.
2.
Mix and Observe:
○
In a test tube, mix a fixed volume of potassium
iodate with sodium sulphite.
○ Add a few drops of starch solution as an indicator.
○ Start the stopwatch and record the time
taken for the solution to turn blue (indicating the formation of iodine-starch
complex).
Observations:
●
Effect of
Concentration: Time taken for the reaction to turn cloudy will vary with
different concentrations of sodium thiosulphate.
●
Effect of
Temperature: Time taken for the reaction to turn cloudy will vary with
different temperatures.
●
Reaction
of Iodide Ion with Hydrogen Peroxide: Time taken for the solution to change
color will vary with different concentrations of iodide ions.
●
Clock
Reaction: Time taken for the solution to turn blue will indicate the
reaction rate.
Result:
●
Successfully studied the effect of concentration
and temperature on the reaction rate between sodium clockthiosulphate and
hydrochloric acid.
●
Successfully studied the reaction rate of
__________ using __________.
Precautions:
●
Ensure all glassware is clean.
●
Measure volumes accurately using measuring
cylinders.
●
Handle chemicals like hydrochloric acid and
hydrogen peroxide carefully.
●
Start the stopwatch immediately after mixing the
solutions to ensure accurate timing.
Viva Questions:
1.
What factors affect the rate of chemical reactions?
2.
How does concentration affect the rate of reaction?
3.
How does temperature affect the rate of reaction?
4.
What is the role of starch in the reaction?
D. ELECTROCHEMISTRY
EXPERIMENT
4
Aim:
To study the variation of cell potential
in the electrochemical cell Zn/Zn²⁺ || Cu²⁺/Cu with the change in concentration
of electrolytes (CuSO₄ or ZnSO₄) at room temperature.
Apparatus
and Chemicals:
- Electrochemical
cell setup (beakers, connecting wires, voltmeter, salt bridge)
- Zinc
electrode (Zn)
- Copper
electrode (Cu)
- Zinc
sulfate (ZnSO₄) solution
- Copper
sulfate (CuSO₄) solution
- Distilled
water
- Voltmeter
- Measuring
cylinders - Electrodes (Zinc and Copper)
Theory:
- Electrochemical
Cell: A device that converts chemical energy into electrical energy through
redox reactions.
-Cell Potential
(Ecell): The difference in electrode potentials between the two electrodes
in an electrochemical cell.
- Nernst
Equation: Describes how the cell potential varies with concentration. For a
general cell:
Procedure:
1. Preparation of
Solutions:
-
Prepare different concentrations of CuSO₄ and ZnSO₄
solutions (e.g., 0.1 M, 0.01 M,
0.001 M) using distilled water.
-
Use separate beakers for each concentration of CuSO₄
and ZnSO₄.
2. Setup of
Electrochemical Cell:
-
Place the zinc electrode in the ZnSO₄ solution.
-
Place the copper electrode in the CuSO₄ solution.
-
Connect the two beakers with a salt bridge filled with
a dilute KCl solution or agar-agar.
3. Measure the Cell Potential:
-
Connect the electrodes to a voltmeter.
-
Record the cell potential for each concentration of
CuSO₄ and ZnSO₄ solution.
4. Repeat for
Various Concentrations:
- Change
the concentration of CuSO₄ and ZnSO₄ solutions as needed.
- Measure
and record the cell potential for each concentration.
Observations:
- Variation in Cell Potential:
- Record
how the cell potential changes with varying concentrations of CuSO₄ and ZnSO₄.
Results:
- Present
the cell potential data as a function of the concentration of the electrolytes.
Analysis:
- Apply
the Nernst equation to understand how the cell potential varies with
concentration.
- Plot
a graph of cell potential versus concentration to analyze the relationship.
Conclusion:
- The
cell potential is influenced by the concentration of electrolytes, as predicted
by the Nernst equation.
Precautions:
- Ensure
that all electrodes are clean and properly immersed in their respective
solutions.
- Confirm
that the salt bridge is correctly filled and connected.
- Measure
the solutions accurately to maintain correct concentrations.
Viva Questions:
1.
What is the Nernst equation and how does it describe
the variation of cell potential with concentration?
2.
How does the concentration of electrolytes affect the
cell potential in an electrochemical cell?
3.
What is the function of the salt bridge in an
electrochemical cell?
4.
How do you determine the standard cell potential from
experimental data?
5.
Why is it important to use different concentrations of
electrolytes in this experiment?
E. CHROMATOGRAPHY
EXPERIMENT 5
AIM
i)
To separate pigments from extracts of leaves and
flowers by paper chromatography and determine the Rf values.
ii)
To separate constituents present in an inorganic
mixture containing two cations with large differences in Rf values.
Apparatus and
Chemicals:
●
Chromatography paper or filter paper
●
Beakers
●
Capillary tubes
●
Solvent (e.g., ethanol, acetone, water, or a
suitable solvent mixture)
●
Leaf or flower extracts
●
Inorganic mixture (containing two cations)
●
Ruler
●
Pencil
●
Glass rod
●
Spatula
Theory:
●
Paper
Chromatography: A technique used to separate and identify components of a
mixture based on their differing rates of movement through a paper medium when
exposed to a solvent.
●
Rf Value
(Retention Factor): The ratio of the distance traveled by the substance to
the distance traveled by the solvent front. Calculated as: Rf=Distance traveled
by the substanceDistance traveled by the solvent frontR_f =
\frac{\text{Distance traveled by the substance}}{\text{Distance traveled by the
solvent
front}}Rf=
Distance traveled by the solvent frontDistance traveled by the substance
Procedure:
Part i: Separation of Pigments from Leaf or Flower Extracts
1.
Preparation of
Extracts:
○
Extract pigments from leaves or flowers using an
appropriate solvent (e.g., ethanol or acetone).
○ Crush the plant material, mix with the
solvent, and filter to obtain a clear extract.
2.
Preparation of
Chromatography Paper:
○
Cut a piece of chromatography or filter paper to
fit the chromatography chamber.
○ Draw a faint pencil line about 2 cm
from the bottom edge of the paper. This will be the baseline.
3.
Application of
Sample:
○
Using a capillary tube, spot a small amount of
the pigment extract onto the baseline of the chromatography paper.
○ Allow the spot to dry completely.
Repeat if necessary to concentrate the spot.
4.
Development of
Chromatogram:
○
Prepare a developing chamber by adding a small
amount of solvent (e.g., a mixture of ethanol and water) to a beaker. The
solvent level should be below the baseline.
○ Place the chromatography paper in the developing chamber and
cover it.
○ Allow the solvent to rise up the paper until it is near the top
edge.
○ Remove the paper from the chamber and allow it to dry.
5.
Determination of
Rf Values:
○
Mark the position of the solvent front on the
paper.
○ Measure the distance traveled by each
pigment spot from the baseline and the distance traveled by the solvent front.
○ Calculate the Rf values using the
formula: Rf=Distance traveled by the pigment Distance traveled by the solvent
frontR_f = \frac{\text{Distance traveled by the pigment}}{\text{Distance
traveled by the solvent front}}Rf= Distance traveled by the
solvent frontDistance traveled by the pigment
Part ii: Separation of Constituents in an Inorganic Mixture
1.
Preparation of
Sample:
○
Dissolve the inorganic mixture containing two
cations in a suitable solvent (e.g., dilute hydrochloric acid or water).
○ Filter the solution to obtain a clear mixture if needed.
2.
Preparation of
Chromatography Paper:
○
Prepare and cut a piece of chromatography paper
as described in Part i.
○ Draw a faint pencil line about 2 cm from the bottom edge of the
paper.
3.
Application of
Sample:
○
Using a capillary tube, spot a small amount of
the inorganic mixture onto the baseline of the chromatography paper.
○ Allow the spot to dry.
4.
Development of
Chromatogram:
○
Prepare a developing chamber with an appropriate
solvent that separates the two cations effectively.
○ Place the chromatography paper in the chamber and cover it.
○ Allow the solvent to rise up the paper.
○ Remove the paper and let it dry.
5.
Determination of
Rf Values:
○
Mark the position of the solvent front on the
paper.
○ Measure the distance traveled by each component and the solvent
front.
○ Calculate the Rf values for each cation
using the formula: Rf=Distance traveled by the cationDistance traveled by the
solvent frontR_f = \frac{\text{Distance traveled by the cation}}{\text{Distance
traveled by the solvent front}}Rf= Distance traveled by the
solvent frontDistance traveled by the cation
Observations:
●
Pigment
Separation:
○
Identify and measure the different pigments
separated on the chromatography paper.
○ Record the Rf values for each pigment.
●
Inorganic
Mixture:
○
Identify and measure the separation of cations.
○ Record the Rf values for each cation.
Results:
●
Pigment
Separation: The pigments from the leaf or flower extract are separated and
their Rf values are determined.
●
Inorganic
Mixture: The two cations in the inorganic mixture are separated based on
their Rf values.
Analysis:
●
Compare the Rf values of the pigments and
cations to their standard values for identification.
●
Discuss the effectiveness of the solvent system
in separating the components.
Conclusion:
●
Paper chromatography effectively separates
pigments and inorganic cations based on their Rf values, allowing for their
identification and analysis.
Precautions:
●
Ensure the baseline on the chromatography paper
is drawn lightly to avoid interference with separation.
●
Avoid immersing the baseline in the solvent
during development.
●
Handle solvents and chemicals with care and in a
well-ventilated area.
Viva Questions:
1.
What is the principle behind paper chromatography?
2.
How do you calculate the Rf value for a substance?
3.
What factors affect the separation of components in
chromatography?
4.
Why is it essential to use a developing chamber in
chromatography?
5.
How can you identify the components in a chromatogram?
F. Preparation of Inorganic Compounds Preparation of double salt
EXPERIMENT 6.1
AIM
To prepare di-benzalacetone through the base-catalyzed
condensation reaction of benzaldehyde with acetone.
Apparatus:
●
Beakers
●
Conical flasks
●
Stirring rods
●
Bunsen burner
●
Glass rod
●
Filter paper
●
Funnel
●
Weighing balance
●
Ice bath Chemicals:
●
Benzaldehyde (C₆H₅CHO)
●
Acetone (CH₃COCH₃)
●
Sodium hydroxide (NaOH) solution (10%)
●
Distilled water Theory:
Di-benzalacetone is synthesized via an aldol condensation
reaction between benzaldehyde and acetone, catalyzed by a strong base.
Procedure:
1.
Preparation of
Reaction Mixture:
○
In a conical flask, mix 10 mL of benzaldehyde
with 5 mL of acetone.
○ Add 20 mL of 10% sodium hydroxide solution to the mixture.
2.
Reaction:
○
Stir the mixture continuously and keep it in an
ice bath to control the temperature and rate of reaction.
3.
Crystallization:
○
Once the reaction is complete, pour the mixture
into a beaker containing ice-cold water.
○ Collect the precipitate by filtration.
4.
Purification:
○
Wash the collected di-benzalacetone with cold
water.
○ Recrystallize the product from ethanol.
5.
Drying:
○
Dry the recrystallized di-benzalacetone on
filter paper.
Observations:
●
Yellow to orange crystals of di-benzalacetone
are obtained.
Result:
●
Di-benzalacetone is successfully prepared.
Precautions:
●
Handle sodium hydroxide with care as it is a
caustic substance.
●
Stir the reaction mixture thoroughly to ensure
complete reaction.
●
Use an ice bath to help with the crystallization
process.
EXPERIMENT 6.2
Objective:
To prepare p-nitroacetanilide by nitrating acetanilide with
a nitrating mixture.
Apparatus:
●
Beakers
●
Conical flasks
●
Stirring rods
●
Bunsen burner
●
Glass rod
●
Filter paper
●
Funnel
●
Weighing balance
●
Ice bath Chemicals:
●
Acetanilide (C₈H₉NO)
●
Nitric acid (HNO₃)
●
Sulfuric acid (H₂SO₄)
●
Distilled water
Theory:
p-Nitroacetanilide is synthesized by nitrating acetanilide
with a mixture of nitric and sulfuric acids. The nitro group is introduced at
the para position relative to the amino group.
Procedure:
1.
Preparation of
Nitrating Mixture:
○
In a beaker, carefully mix concentrated nitric
acid with sulfuric acid in a 1:2 ratio. Cool the mixture in an ice bath.
2.
Nitration:
○
Slowly add 5 g of acetanilide to the cooled
nitrating mixture while stirring continuously.
○ Maintain the temperature below 10°C to control the rate of
reaction.
3.
Crystallization:
○
After completion of the reaction, pour the
mixture into ice-cold water to precipitate p-nitroacetanilide.
○ Collect the precipitate by filtration.
4.
Purification:
○
Wash the collected solid with cold water.
○ Recrystallize p-nitroacetanilide from ethanol.
5.
Drying:
○
Dry the recrystallized p-nitroacetanilide on
filter paper.
Observations:
●
Pale yellow crystals of p-nitroacetanilide are
obtained.
Result:
●
p-Nitroacetanilide is successfully prepared.
Precautions:
●
Handle nitric and sulfuric acids with care.
●
Perform the reaction in an ice bath to manage
the exothermic nature of the reaction.
●
Ensure thorough mixing for uniform nitration.
EXPERIMENT 6.3
Objective:
To prepare the 2-naphthol aniline dye, also known as
Aniline Yellow.
Apparatus:
●
Beakers
●
Conical flasks
●
Stirring rods
●
Bunsen burner
●
Glass rod
●
Filter paper
●
Funnel
●
Weighing balance
●
Ice bath
Chemicals:
●
2-Naphthol (C₁₀H₇OH)
●
Aniline (C₆H₅NH₂)
●
Sodium hydroxide (NaOH) solution
●
Distilled water
Theory:
2-Naphthol reacts with aniline in the presence of sodium
hydroxide to form a dye, known as aniline yellow, which is a type of azo dye.
Procedure:
1.
Preparation of
Reaction Mixture:
○
Dissolve 5 g of 2-naphthol in 50 mL of sodium
hydroxide solution in a beaker.
○ Add 5 g of aniline to this solution and stir continuously.
2.
Reaction:
○
Heat the mixture gently to complete the
reaction.
3.
Crystallization:
○
After the reaction, pour the mixture into
ice-cold water to precipitate the dye.
○ Collect the precipitate by filtration.
4.
Purification:
○
Wash the dye with cold water.
○ Recrystallize the dye from ethanol.
5.
Drying:
○
Dry the recrystallized product on filter paper.
Observations:
●
Bright yellow crystals of the dye (Aniline
Yellow) should be obtained.
Result:
●
2-Naphthol Aniline dye (Aniline Yellow) is
successfully prepared.
Precautions:
●
Handle 2-naphthol and aniline with care.
●
Maintain stirring during the reaction to ensure
complete reaction.
●
Use an ice bath for effective crystallization.
G.
ORGANIC CHEMISTRY
Tests for the Functional Groups Present in
Organic Compounds
EXPERIMENT 7.1
1. Test for
Unsaturation (Alkenes and Alkynes)
Objective: To
detect the presence of carbon-carbon double or triple bonds in organic
compounds.
Reagents:
- Bromine
water
- Potassium
permanganate solution
Procedure:
- Bromine Water Test:
1. Add
2-3 mL of bromine water to a test tube.
2. Add
2-3 drops of the organic compound to the test tube.
3.
Shake the mixture.
Observation:
-
Positive: Decolorization of the reddish-brown bromine
water indicates the presence of unsaturation.
-
Negative: No change in color.
Potassium
Permanganate Test:
1.
Add 2-3 drops of the organic compound to a test tube
containing 2-3 mL of dilute potassium permanganate solution.
2.
Shake the mixture gently.
Observation:
-
Positive: Decolorization of the purple potassium
permanganate and formation of a brown precipitate indicates unsaturation.
-
Negative: No change in color.
2. Test for
Alcoholic Group
Objective: To detect the presence of alcohols in organic compounds.
Reagents:
- Lucas
reagent (ZnCl₂ in concentrated HCl)
- Sodium
metal
Procedure:
- Lucas Test:
1. Add
2-3 mL of Lucas reagent to a test tube.
2. Add
2-3 drops of the organic compound.
3.
Shake the mixture and let it stand at room temperature.
Observation:
- Positive:
Formation of a cloudy solution indicates secondary or tertiary alcohols.
- Negative:
No change or very slow formation of turbidity indicates primary alcohols.
- Sodium Metal Test:
1. Place
a small piece of sodium metal in a clean, dry test tube.
2.
Add 2-3 mL of the organic compound.
Observation:
-
Positive: Effervescence due to the evolution of
hydrogen gas indicates the presence of alcohols.
-
Negative: No effervescence.
3. Test for Phenolic Group
Objective:To detect the presence of phenolic hydroxyl
groups in organic compounds.
Reagents:
- Ferric
chloride solution - Sodium hydroxide solution
Procedure:
- Ferric
Chloride Test:
1. Add
2-3 mL of the organic compound to a test tube.
2.
Add 2-3 drops of ferric chloride solution.
Observation:
-
Positive: Formation of a violet, blue, or green complex
indicates the presence of phenolic hydroxyl groups.
-
Negative: No color change.
-
Sodium Hydroxide Test:
1. Add 2-3 mL of sodium hydroxide solution to the organic
compound.
Observation:
-
Positive: Formation of a darker-colored solution or
precipitate indicates phenolic hydroxyl groups.
-
Negative: No significant change.
4. Test for Aldehydic Group
Objective:To detect the presence of aldehyde groups in
organic compounds.
Reagents:
- Tollens'
reagent - Fehling’s solution
Procedure:
- Tollens'
Test:
1. Add
2-3 mL of Tollens' reagent to a clean test tube.
2. Add
2-3 drops of the organic compound.
3.
Heat gently in a water bath.
Observation:
-
Positive: Formation of a silver mirror on the inner
surface of the test tube indicates the presence of aldehydes.
-
Negative: No silver mirror is observed.
-
Fehling's Test:
1. Mix
equal volumes of Fehling’s Solution A and Solution B in a test tube.
2. Add
2-3 drops of the organic compound.
3. Heat
the mixture gently.
Observation:
- Positive:
Formation of a red or orange precipitate indicates the presence of aldehydes.
- Negative:
No precipitate forms.
5. Test for Ketonic Group
Objective: To detect the presence of ketone groups in
organic compounds.
Reagents:
- 2,4-Dinitrophenylhydrazine (2,4-DNP) solution
Procedure:
1. Add
2-3 mL of 2,4-Dinitrophenylhydrazine solution to a test tube.
2. Add
2-3 drops of the organic compound.
3.
Shake the mixture and observe.
Observation:
- Positive:
Formation of a yellow or orange precipitate (2,4-dinitrophenylhydrazone)
indicates the presence of ketones.
- Negative:
No precipitate forms.
6. Test for Carboxylic Group
Objective: To detect the presence of carboxylic acid groups
in organic compounds.
Reagents:
- Sodium
bicarbonate solution
- Litmus
paper
Procedure:
- Sodium
Bicarbonate Test:
1. Add
2-3 mL of sodium bicarbonate solution to a test tube.
2. Add
2-3 drops of the organic compound.
3.
Observe the reaction.
Observation:
-
Positive: Formation of effervescence (bubbles) due to
carbon dioxide gas indicates the presence of carboxylic acids.
-
Negative: No effervescence.
-
Litmus Paper Test:
1. Dissolve
a small amount of the organic compound in water.
2.
Test the solution with red and blue litmus paper.
Observation:
-
Positive: The solution turns blue litmus paper red,
indicating the presence of carboxylic acids.
-
Negative: No change in litmus paper color.
7. Test for Amino (Primary) Group
Objective:To detect the presence of primary amino groups in
organic compounds.
Reagents:
- Ninhydrin
solution
- Benzaldehyde
Procedure:
- Ninhydrin
Test:
1. Add
2-3 mL of ninhydrin solution to a test tube.
2. Add
2-3 drops of the organic compound.
3.
Heat gently in a water bath.
Observation:
-
Positive: Formation of a blue or purple color indicates
the presence of primary amino groups.
-
Negative: No color change.
-
Benzaldehyde Test:
1. Mix a
few drops of benzaldehyde with the organic compound in a test tube.
2.
Observe any reaction.
Observation:
-
Positive: Formation of a colored product indicates the
presence of primary amino groups.
-
Negative: No color change.
H. Qualitative
analysis Determination of one cation and one anion in a given salt
Aim:
To detect one cation and one anion from the given salt sample using
systematic qualitative analysis.
Theory:
The solubility product principle states that a salt precipitates when the
ionic product of its ions exceeds the solubility product (Ksp). The common ion
effect is used to control the solubility of salts in solution. Identification
is based on specific reactions that produce characteristic precipitates,
colors, or gases.
Materials Required:
- Boiling
tube
- Test
tubes
- Measuring
cylinder
- Test
tube stand
- Test
tube holder
- Delivery
tube
- Corks
- Filter
paper
- Reagents:
Dilute H₂SO₄, Na₂CO₃, KI, NH₄OH, NaOH, BaCl₂, AgNO₃, etc.
Procedure for Anion Detection
Step 1: Preliminary Test with Dilute Sulphuric Acid
1. Sample
Preparation:
- Place
0.1 g of the salt in a clean, dry test tube.
- Add
1-2 mL of dilute sulphuric acid (H₂SO₄).
2. Observation
at Room Temperature:
- Observe
any immediate reaction (effervescence, gas evolution).
3. Observation
on Warming:
- Gently
heat the test tube if no reaction occurs at room temperature.
- Identify
the evolved gas using the following criteria:
- CO₂:
Effervescence; turns lime water (Ca(OH)₂) milky.
- H₂S: Rotten egg
smell; turns lead acetate paper black.
- SO₂: Pungent
smell; turns acidified potassium dichromate (K₂Cr₂O₇) green.
- NO₂: Brown
fumes; turns acidified potassium iodide-starch solution blue.
- CH₃COOH:
Vinegar smell; turns blue litmus paper red.
Step 2: Preparation of Sodium Carbonate Extract
- Preparation:
- Mix 1
g of the salt with 3 g of solid sodium carbonate (Na₂CO₃).
- Add
15 mL of distilled water.
- Boil
the mixture for 10 minutes in a porcelain dish or boiling tube.
- Cool
and filter the mixture to obtain the filtrate, labeled as sodium
carbonate extract.
Step 3: Confirmatory Tests for Anions
Carbonate (CO₃²⁻)
- Test with Dilute Sulphuric Acid:
- Add
dilute H₂SO₄ to the salt sample. Effervescence and CO₂ gas indicate
CO₃²⁻.
- Lime Water Test:
- Pass
the evolved gas through lime water (Ca(OH)₂). The formation of a white
precipitate (CaCO₃) confirms CO₃²⁻.
Sulphide (S²⁻)
- Test with Dilute Sulphuric Acid:
- Add
dilute H₂SO₄ to the salt sample. Rotten egg smell indicates H₂S gas.
- Lead Acetate Test:
- Use
lead acetate paper. Blackening confirms S²⁻.
- Sodium Nitroprusside Test:
- Add
sodium nitroprusside to the alkaline solution. Purple/violet color
confirms S²⁻.
Sulphite (SO₃²⁻)
- Test with Dilute Sulphuric Acid:
- Add
dilute H₂SO₄ to the salt sample. Pungent SO₂ gas indicates SO₃²⁻.
- Potassium Permanganate Test:
- Decolorization
of acidified potassium permanganate (KMnO₄) solution confirms SO₃²⁻.
Sulphate (SO₄²⁻)
- Barium Chloride Test:
- Add
BaCl₂ to the solution of the salt. A white precipitate of barium sulphate
(BaSO₄) indicates SO₄²⁻, which is insoluble in dilute HCl.
Nitrite (NO₂⁻)
- Test with Dilute Sulphuric Acid:
- Add
dilute H₂SO₄ to the salt and warm. Brown fumes indicate NO₂⁻.
- Potassium Iodide-Starch Test:
- Blue
color on KI-starch paper confirms NO₂⁻.
- Sulphanilic Acid and
1-Naphthylamine Test:
- Red
color indicates NO₂⁻.
Nitrate (NO₃⁻)
- Brown Ring Test:
- Add
freshly prepared ferrous sulphate (FeSO₄) solution to the nitrate
solution.
- Carefully
add concentrated sulphuric acid (H₂SO₄) along the side of the test tube.
- A
brown ring at the junction of the two liquids indicates NO₃⁻.
Chloride (Cl⁻)
- Silver Nitrate Test:
- Add
AgNO₃ solution to the salt solution. A white precipitate of AgCl
indicates Cl⁻, which is soluble in NH₄OH.
Bromide (Br⁻)
- Silver Nitrate Test:
- Add
AgNO₃ solution to the salt solution. A pale yellow precipitate of AgBr
indicates Br⁻, which is sparingly soluble in NH₄OH.
Iodide (I⁻)
- Silver Nitrate Test:
- Add
AgNO₃ solution to the salt solution. A yellow precipitate of AgI
indicates I⁻, which is insoluble in NH₄OH.
Phosphate (PO₄³⁻)
- Ammonium Molybdate Test:
- Add
ammonium molybdate to the nitric acid (HNO₃) solution of the salt. A
yellow precipitate of ammonium phosphomolybdate indicates PO₄³⁻.
Oxalate (C₂O₄²⁻)
- Calcium Chloride Test:
- Add
calcium chloride (CaCl₂) to the solution of the salt. A white precipitate
of calcium oxalate (CaC₂O₄) indicates C₂O₄²⁻, which is soluble in acetic
acid.
Acetate (CH₃COO⁻)
- Test with Dilute Sulphuric Acid:
- Add
dilute H₂SO₄ to the salt sample. Vinegar smell indicates CH₃COO⁻.
- Ester Formation Test:
- Heat
with ethanol and conc. H₂SO₄. Fruity ester smell confirms CH₃COO⁻.
- Ferric Chloride Test:
- Add
neutral ferric chloride (FeCl₃) solution. Deep red color that disappears
on boiling confirms CH₃COO⁻.
Procedure for Cation Detection
Step 1: Preliminary Examination
- Physical Observation:
- Note
the color, smell, and solubility of the salt.
Step 2: Systematic Analysis of Cations
Lead (Pb²⁺)
- Potassium Iodide Test:
- Add
KI solution to the salt solution. Yellow precipitate (PbI₂) indicates
Pb²⁺.
Copper (Cu²⁺)
- Ammonium Hydroxide Test:
- Add
NH₄OH to the salt solution. Blue precipitate (Cu(OH)₂) or deep blue
solution (tetraamminecopper(II) complex) confirms Cu²⁺.
Arsenic (As³⁺)
- Silver Nitrate Test:
- Add
AgNO₃ to the neutral or slightly acidic solution. Yellow precipitate of
Ag₃AsO₄ indicates As³⁺.
Aluminium (Al³⁺)
- Sodium Hydroxide Test:
- Add
NaOH to the salt solution. White precipitate of Al(OH)₃ soluble in excess
NaOH indicates Al³⁺.
Iron (Fe³⁺)
- Sodium Hydroxide Test:
- Add
NaOH to the salt solution. Brown precipitate (Fe(OH)₃) indicates Fe³⁺.
- Potassium Ferrocyanide Test:
- Add
potassium ferrocyanide to the salt solution. A blue precipitate of ferric
ferrocyanide indicates Fe³⁺.
Manganese (Mn²⁺)
- Sodium Hydroxide Test:
- Add NaOH
to the salt solution. White precipitate of Mn(OH)₂ turning brown
indicates Mn²⁺.
- Sodium Bismuthate Test:
- Add
sodium bismuthate to the acidic solution. Pink color indicates Mn²⁺.
Nickel (Ni²⁺)
- Dimethylglyoxime Test:
- Add
dimethylglyoxime to the ammoniacal solution. A red precipitate of nickel
dimethylglyoximate indicates Ni²⁺.
Zinc (Zn²⁺)
- Sodium Hydroxide Test:
- Add
NaOH to the salt solution. White precipitate (Zn(OH)₂) soluble in excess
NaOH indicates Zn²⁺.
Cobalt (Co²⁺)
- Sodium Hydroxide Test:
- Add
NaOH to the salt solution. Blue precipitate of Co(OH)₂ turning pink on
exposure indicates Co²⁺.
Calcium (Ca²⁺)
- Ammonium Hydroxide Test:
- Add
NH₄OH to the salt solution. White precipitate (Ca(OH)₂) indicates Ca²⁺.
- Flame Test:
- Dip
a clean platinum wire into the salt solution and place it in a
non-luminous flame. Brick-red flame indicates Ca²⁺.
Strontium (Sr²⁺)
- Ammonium Sulphate Test:
- Add
(NH₄)₂SO₄ to the salt solution. A white precipitate of SrSO₄ indicates
Sr²⁺.
- Flame Test:
- Dip
a clean platinum wire into the salt solution and place it in a
non-luminous flame. Crimson red flame indicates Sr²⁺.
Barium (Ba²⁺)
- Potassium Chromate Test:
- Add
K₂CrO₄ to the salt solution. Yellow precipitate of BaCrO₄ indicates Ba²⁺.
- Flame Test:
- Dip
a clean platinum wire into the salt solution and place it in a
non-luminous flame. Green flame indicates Ba²⁺.
Magnesium (Mg²⁺)
- Sodium Hydroxide Test:
- Add
NaOH to the salt solution. White precipitate of Mg(OH)₂ in presence of
NH₄Cl indicates Mg²⁺.
Ammonium (NH₄⁺)
- Sodium Hydroxide Test:
- Warm
the salt solution with NaOH. Ammonia gas (NH₃) evolved, detected by its
characteristic smell and turning red litmus paper blue, indicates NH₄⁺.
Precautions
- Use
clean and dry apparatus to avoid contamination.
- Handle
chemicals, especially acids and bases, with care to avoid spills and
burns.
- Work
in a well-ventilated area or under a fume hood to avoid inhaling harmful
fumes.
- Dispose
of chemical waste properly according to safety guidelines.
- Use
gloves and safety goggles to protect skin and eyes.
- Label
all reagents and solutions correctly to avoid mix-ups.
- Do
not inhale gases directly; use appropriate techniques for gas
identification.
- Ensure
the complete dissolution of salts when preparing solutions.
Viva Voce Questions
1. What
is qualitative analysis?
- Qualitative
analysis is the determination of the chemical composition of a substance
by identifying its constituent elements or ions.
2. What
is the solubility product?
- The
solubility product (Ksp) is the product of the concentrations of the ions
of a sparingly soluble salt, each raised to the power of its coefficient
in the balanced chemical equation.
3. Explain
the common ion effect.
- The
common ion effect is the shift in equilibrium caused by the addition of
an ion common to the solute, which suppresses the solubility of the
solute.
4. Why
is it important to use distilled water in chemical analysis?
- Distilled
water is free from impurities that could interfere with the reactions and
give erroneous results.
5. What
observations indicate the presence of CO₃²⁻?
- Effervescence
with dilute H₂SO₄ and the production of a gas that turns lime water milky
(CO₂).
6. What
is the significance of a purple/violet color in the sodium nitroprusside test?
- A
purple/violet color indicates the presence of sulphide ions (S²⁻).
7. Describe
the reaction of Cu²⁺ with NH₄OH.
- Cu²⁺
reacts with NH₄OH to form a blue precipitate of copper(II) hydroxide,
which dissolves in excess NH₄OH to form a deep blue tetraamminecopper(II)
complex.
8. How
can you confirm the presence of acetate ions (CH₃COO⁻)?
- By
heating with ethanol and conc. H₂SO₄ to produce a fruity ester smell, or
by adding FeCl₃ to produce a deep red color that disappears on boiling.
PROJECTS
1. Study of
the Presence of Oxalate Ions in Guava Fruit at Different Stages of Ripening
**Objective**:
Determine the concentration of oxalate ions in guava fruit
at various stages of ripening.
**Materials**:
- Guava fruits (unripe, partially ripe, fully ripe)
- Distilled water
- 0.05 M KMnO₄
solution
- 1 M H₂SO₄ solution
- Burette, pipette, conical flask
- Mortar and pestle
- Filter paper
Procedure:
1. **Preparation of Extract**:
- Crush 50g of guava fruit with 50 mL
distilled water.
- Filter to obtain a clear extract.
2. Titration:
- Take 10 mL of the extract, add 10 mL of
1 M H₂SO₄.
- Heat to 60°C and titrate with 0.05 M
KMnO₄
until a permanent pink color persists.
3. **Calculation**:
- Calculate the concentration of oxalate
ions using the titration data and the equation:
\[
2MnO_4^- + 5C_2O_4^{2-} + 16H^+
\rightarrow 2Mn^{2+} + 10CO_2 + 8H_2O
\]
#### **Observation**:
Record the volume of KMnO₄ used for different ripening stages.
### 2. Study of Quantity of Casein Present in Different
Samples of Milk
#### **Objective**:
Determine the amount of casein in various milk samples.
#### **Materials**:
- Milk samples (cow, buffalo, goat, soy)
- Acetic acid (vinegar)
- Beakers, filter paper
- Analytical balance
- Hot plate
#### **Procedure**:
1. **Precipitation of Casein**:
- Heat 20 mL of milk to 40-50°C.
- Add acetic acid dropwise until casein
precipitates.
2. **Filtration**:
- Filter and wash the casein precipitate
with distilled water.
3. **Drying and Weighing**:
- Dry the precipitate and weigh it.
#### **Observation**:
Compare the amount of casein in different milk samples.
### 3. Preparation of Soybean Milk and Its Comparison with
Natural Milk
#### **Objective**:
Prepare soybean milk and compare it with natural milk
regarding curd formation and temperature effects.
#### **Materials**:
- Soybeans, natural milk
- Vinegar or lemon juice
- Thermometer, beakers
- Cheesecloth, hot plate
#### **Procedure**:
1. **Preparation of Soybean Milk**:
- Soak 100g of soybeans overnight, blend
with 500 mL of water, and filter.
2. **Curd Formation**:
- Heat 100 mL of each milk type to
40-50°C.
- Add vinegar or lemon juice, observe curd
formation.
3. **Effect of Temperature**:
- Repeat curd formation at different
temperatures (20°C, 40°C, 60°C).
#### **Observation**:
Compare curd formation and temperature effects on both milk
types.
###
4. Study of the Effect of Potassium Bisulphate as Food Preservative
#### **Objective**:
Study the effect of potassium bisulphate on food
preservation under various conditions.
#### **Materials**:
- Fresh food samples (fruits, vegetables)
- 0.1% potassium bisulphate solution
- Beakers, refrigerator, incubator
#### **Procedure**:
1. **Treatment of Food Samples**:
- Dip food samples in the preservative
solution for 10 minutes.
- Store samples at different conditions
(room temperature, refrigerated, incubated).
2. **Observation**:
- Check for spoilage signs (color,
texture, odor) periodically.
- Measure pH periodically.
#### **Observation**:
Compare preservation efficacy under different conditions.
###
5. Study of Digestion of Starch by Salivary Amylase
#### **Objective**:
Study the digestion of starch by salivary amylase and the
effect of pH and temperature.
#### **Materials**:
- Starch solution, fresh saliva
- Iodine solution
- Test tubes, pH buffer solutions
- Water bath, thermometer
#### **Procedure**:
1. **Digestion Experiment**:
- Mix 5 mL of starch solution with 1 mL of
saliva.
- Incubate at different temperatures
(20°C, 37°C, 60°C), test with iodine.
2. **Effect of pH**:
- Mix starch solution, saliva, buffer
solution in test tubes.
- Incubate at 37°C, test with iodine.
#### **Observation**:
Record time for blue-black color disappearance to determine
optimal amylase activity conditions.
###
6. Comparative Study of the Rate of Fermentation of Different Materials
#### **Objective**:
Compare the rate of fermentation of wheat flour, gram flour,
potato juice, and carrot juice.
#### **Materials**:
- Wheat flour, gram flour, potato juice, carrot juice
- Yeast
- Sugar
- Warm water
- Test tubes, beakers
- Balloon or gas syringe
#### **Procedure**:
1. **Preparation**:
- Mix each material with yeast, sugar, and
warm water in separate test tubes.
2. **Fermentation**:
- Attach a balloon or gas syringe to each
test tube to collect the gas produced.
- Measure the volume of gas produced at
regular intervals.
#### **Observation**:
Compare the volume of gas produced by different materials
over time to determine the rate of fermentation.
###
7. Extraction of Essential Oils from Saunf, Ajwain, and Ilaichi
#### **Objective**:
Extract essential oils from saunf (aniseed), ajwain (carum),
and illaichi (cardamom).
#### **Materials**:
- Saunf, ajwain, illaichi
- Distilled water
- Distillation apparatus
- Analytical balance
#### **Procedure**:
1. **Preparation**:
- Weigh a known quantity of each seed.
- Crush the seeds and mix with distilled
water.
2. **Distillation**:
- Set up the distillation apparatus.
- Distill the mixture to extract the
essential oil.
3. **Collection**:
- Collect the essential oil in a separate
container.
- Measure the volume of oil extracted.
#### **Observation**:
Compare the amount of essential oil extracted from each type
of seed.
###
8. Study of Common Food Adulterants in Fat, Oil, Butter, Sugar, Turmeric
Powder, Chilli Powder, and Pepper
#### **Objective**:
Identify common adulterants in various food items.
#### **Materials**:
- Samples of fat, oil, butter, sugar, turmeric powder,
chilli powder, pepper
- Chemicals for testing (e.g., iodine, hydrochloric acid,
water)
- Test tubes, beakers
#### **Procedure**:
1. **Testing for Adulterants**:
- Perform specific tests for each food
item (e.g., iodine test for starch in sugar, hydrochloric acid test for chalk
powder in turmeric).
2. **Observation**:
- Observe color changes, precipitates, or
other reactions indicating the presence of adulterants.
#### **Observation**:
Record the results of tests for each food sample and
identify any adulterants present.
These projects incorporate chemical equations and diagrams,
providing a scientific and realistic approach suitable for the 12th-grade
chemistry curriculum for the Madhya Pradesh Board.
END
