CBSE BOARD CHEMISTRY PROJECTS CLASS 12

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.

PROJECT - 01

Aim

To study the presence and variation in the concentration of oxalate ions in guava fruit at different stages of ripening.

Introduction

Guava is a tropical fruit that is rich in vitamins, minerals, and dietary fibers. One of its chemical components is oxalic acid, which occurs in the form of oxalate ions. The concentration of oxalate ions changes as the fruit ripens. This project aims to analyze the amount of oxalate ions in guava fruit at different stages of ripening.

Theory

Oxalic acid is a dicarboxylic acid and a natural constituent of many plants. It forms oxalate salts with various metal ions, which can be detected and quantified using titration techniques. By titrating a solution of guava extract with potassium permanganate, the amount of oxalate ions can be determined.

Materials Required

1. Fresh guava fruits at different stages of ripening (raw, semi-ripe, ripe)

2. 0.1 M potassium permanganate (KMnO₄) solution

3. Dilute sulfuric acid (H₂SO₄)

4. Distilled water

5. Burette

6. Pipette

7. Conical flask

8. Beaker

9. Mortar and pestle

10. Filter paper

Procedure

1. Preparation of Guava Extract:

   • Take 50 g of guava (at a specific stage of ripening) and crush it using a mortar and pestle.

   • Add 50 mL of distilled water to the crushed guava and mix thoroughly.

   • Filter the mixture to obtain a clear guava extract.

2. Titration Setup:

   • Take 10 mL of the guava extract in a conical flask.

   • Add 10 mL of dilute sulfuric acid to the extract to acidify the solution.

   • Titrate the solution against 0.1 M potassium permanganate solution.

   • Add KMnO₄ dropwise until a persistent pink color appears, indicating the endpoint.

3. Record Observations:

   • Note the volume of KMnO₄ used to reach the endpoint.

   • Repeat the experiment for each stage of ripening and for consistent readings.

Observations

Calculations

Given:

• Molarity of KMnO₄ = 0.1 M

• Reaction between oxalate ions and KMnO₄:

2 MnO4− + 5 C2O42− + 16H+ → 2 Mn+2 + 10 CO2 + 8 H2O2 

From the stoichiometry, 2 moles of KMnO₄ react with 5 moles of oxalate ions.

Calculation for Raw Guava:

Volume of KMnO₄ used = 15.5 mL = 0.0155 L

Moles of KMnO₄ = Molarity × Volume (L)=0.1 × 0.0155=0.00155 moles

Moles of KMnO₄ = Molarity x Volume (L) = 0.1 x 0.0155 = 0.00155 moles

Moles of oxalate ions=52 × Moles of KMnO₄=52×0.00155=0.003875 moles

Moles of oxalate ions = 5/2 x Moles of KMnO₄ = 5/2 x 0.00155 = 0.003875 moles

Repeat similar calculations for semi-ripe and ripe guava.

Results

• The concentration of oxalate ions was found to be highest in raw guava and decreased with ripening.

Conclusion

The study concludes that the concentration of oxalate ions decreases with the ripening of guava. This may be attributed to metabolic changes during the ripening process, such as the breakdown of oxalic acid into simpler compounds.

Precautions

1. Use freshly prepared guava extract for each titration.

2. Add potassium permanganate dropwise to avoid overshooting the endpoint.

3. Ensure all apparatus are clean before use.

4. Conduct the experiment in a well-ventilated area.

Bibliography

1. NCERT Chemistry Class XII Textbook

2. [Relevant Chemistry Practical Manual]

3. Online resources: [Insert sources if any]

PROJECT - 02

Aim

To determine the quantity of casein present in different samples of milk (e.g., cow's milk, buffalo's milk, and toned milk).

Introduction

Casein is a protein found in milk, constituting about 80% of its total protein content. It is an important component, widely used in the food industry and in the preparation of adhesives, paints, and other products. The protein is suspended in milk in the form of calcium caseinate. Upon acidification, it coagulates, making it possible to measure its content. This experiment investigates the quantity of casein in different types of milk.

Materials Required

1. Beakers (250 mL)

2. Measuring cylinder

3. Funnel

4. Filter paper

5. Glass rod

6. Weighing balance

7. Distilled water

8. Dilute acetic acid (1%)

9. Milk samples:

   • Cow’s milk

   • Buffalo’s milk

   • Toned milk

Theory

When dilute acetic acid is added to milk, casein is precipitated as it is insoluble in acidic conditions. By filtering and weighing the precipitate, the amount of casein in milk can be determined.

Procedure

1. Preparation of Milk Samples:

   • Take 20 mL of each milk sample in separate beakers.

2. Precipitation of Casein:

   • Add 20 mL of distilled water to each milk sample.

   • Heat gently to about 40°C.

   • Slowly add 1% acetic acid dropwise with constant stirring until curdling occurs.

3. Filtration:

   • Filter the mixture through a pre-weighed filter paper using a funnel.

   • Wash the residue on the filter paper with distilled water to remove any residual milk solids.

4. Drying and Weighing:

   • Allow the filter paper with casein to dry completely in air.

   • Weigh the dried residue along with the filter paper.

   • Subtract the weight of the empty filter paper to determine the weight of casein.

5. Repeat for all Milk Samples:

   • Follow the same procedure for cow's milk, buffalo's milk, and toned milk.

Observations

Calculations

Weight of Casein=(Weight of Filter Paper + Casein) − Weight of Filter Paper

For cow’s milk: 0.90 g = 2.10 g − 1.20 g

Similar calculations are done for buffalo's milk and toned milk.

Results

The quantity of casein in different milk samples is:

• Cow’s Milk: 0.90 g per 20 mL

• Buffalo’s Milk: 1.05 g per 20 mL

• Toned Milk: 0.80 g per 20 mL

Conclusion

Buffalo’s milk contains the highest amount of casein, followed by cow’s milk, while toned milk has the least. This result aligns with the nutritional differences in milk types.

Precautions

1. Use fresh milk samples for accurate results.

2. Add acetic acid dropwise to avoid over-acidification.

3. Ensure that the filter paper is completely dry before weighing.

4. Conduct the experiment in a clean environment to avoid contamination.

PROJECT - 03

Objective

To prepare soybean milk and compare it with natural milk concerning curd formation, the effect of temperature on curd formation, and other related properties.

Introduction

Milk is a vital source of nutrition for humans, with natural milk derived from animals such as cows and buffaloes being the most common. Plant-based alternatives like soybean milk are gaining popularity due to dietary preferences and lactose intolerance. This project explores the preparation of soybean milk and its properties compared to natural milk.

Materials and Equipment

• Soybeans

• Natural milk (cow or buffalo milk)

• Lemon juice or vinegar (as a coagulant)

• Thermometer

• Beakers

• Strainer or muslin cloth

• Heating equipment (stove or hot plate)

• Bowls for curd formation

• Curd starter

Procedure

1. Preparation of Soybean Milk

1. Soak 100 g of soybeans in water overnight (8-12 hours).

2. Drain and rinse the soaked soybeans.

3. Grind the soybeans with 500 ml of water to make a smooth paste.

4. Strain the paste through a muslin cloth to extract the liquid.

5. Boil the extracted liquid for 10 minutes, stirring continuously to avoid burning.

6. Cool and store the soybean milk for further analysis.

2. Preparation of Curd

1. Divide soybean milk and natural milk into equal portions (100 ml each).

2. Add 1 teaspoon of curd starter to each portion.

3. Keep the samples at different temperatures (e.g., room temperature, 30°C, 40°C).

4. Observe and record curd formation after 6-8 hours.

Observation and Data Analysis

Table 1: Comparison of Properties

Table 2: Curd Formation

Comparison of Soybean Milk with Natural Milk

• Protein Content: Both are rich in proteins, but natural milk has casein, while soybean milk has soy proteins.

• Lactose: Soybean milk is lactose-free, making it suitable for lactose-intolerant individuals.

• Curd Formation: Natural milk forms curd due to its casein content, which reacts with lactic acid. Soybean milk lacks casein and does not form curd under normal conditions.

Effect of Temperature on Curd Formation

Natural milk showed quicker curd formation at higher temperatures (40°C). Soybean milk did not form curd, highlighting the absence of casein, which is essential for curd formation.

Conclusion

1. Soybean milk is a viable alternative to natural milk, especially for those with dietary restrictions.

2. Natural milk forms curd effectively due to its casein content, which is absent in soybean milk.

3. Temperature significantly influences the curd formation process in natural milk but does not impact soybean milk.

Bibliography

1. "Textbook of Biology for Class XII," NCERT.

2. Websites: CBSE Resource Portal, [Scientific Journals].

3. Reference Books: "Food Science and Technology" by B. Srilakshmi.

PROJECT - 04

Aim

To study the effect of potassium bisulphate as a food preservative under various conditions like temperature, concentration, and time.

Theory

Potassium bisulphate is commonly used in the food industry to inhibit microbial growth. It works by creating a slightly acidic environment that hinders the metabolic processes of microorganisms.Chemical Formula: KHSO₄Molecular Weight: 136.17 g/mol

Materials and Apparatus

1. Food samples (e.g., fruit juices, chopped vegetables, milk)

2. Potassium bisulphate (analytical grade)

3. Beakers

4. Thermometer

5. Incubator

6. pH meter

7. Stopwatch

8. Weighing balance

9. Sterile petri dishes

10. Refrigerator

Procedure

1. Preparation of Food Samples:

   • Take three food samples: fresh orange juice, chopped carrots, and milk.

   • Divide each into three equal portions.

2. Addition of Potassium Bisulphate:

   • Add different concentrations of potassium bisulphate (0.5%, 1.0%, and 1.5% by weight) to each portion. Label the samples accordingly.

3. Storage Conditions:

   • Store one set at room temperature (~25°C), one in a refrigerator (~5°C), and one in an incubator (~37°C).

4. Observation Period:

   • Observe the samples for spoilage indicators (odor, appearance, and microbial growth) every 24 hours over 7 days.

5. Control Group:

   • Maintain an untreated sample for each food type as a control.

Observations

Table 1: Effect on Orange Juice (Room Temperature)

Table 2: Effect on Milk (Refrigerated)

Table 3: Effect on Chopped Carrots (Incubator)

Analysis and Interpretation

1. Higher concentrations of potassium bisulphate (1.0% and 1.5%) significantly delayed spoilage compared to lower concentrations.

2. Refrigeration enhanced the preservative effect, with even low concentrations showing effectiveness.

3. Elevated temperatures accelerated spoilage in untreated and low-concentration samples, highlighting the importance of optimal storage conditions.

Conclusion

The study demonstrates that potassium bisulphate effectively preserves food by delaying spoilage, particularly when used in higher concentrations and under cooler storage conditions.

Bibliography

1. NCERT Chemistry Textbook for Class XII.

2. Research articles on food preservation methods.

3. Laboratory Manual for Chemistry, CBSE.

PROJECT - 05

Objective:

To study the digestion of starch by salivary amylase and analyze the effect of varying pH and temperature on the rate of starch digestion.

Introduction:

Salivary amylase is an enzyme produced in the salivary glands that catalyzes the breakdown of starch into maltose. Enzymes are highly sensitive to changes in environmental conditions such as pH and temperature. This project investigates the role of salivary amylase in starch digestion and how varying pH and temperature influence its activity.

Materials Required:

1. Test tubes

2. Beakers

3. Iodine solution

4. Starch solution (1%)

5. Saliva sample

6. pH solutions (pH 3, pH 7, and pH 9)

7. Water bath

8. Thermometer

9. Stopwatch

10. Dropper

Procedure:

Part A: Digestion of Starch by Salivary Amylase

1. Prepare a 1% starch solution by dissolving starch in boiling water.

2. Add 5 mL of the starch solution into a test tube.

3. Collect a fresh saliva sample and dilute it with an equal volume of distilled water.

4. Add 1 mL of the diluted saliva to the starch solution.

5. Place the test tube at room temperature and take samples every 2 minutes.

6. Test each sample with iodine solution. Record the time taken for the blue-black color (indicating the presence of starch) to disappear.

Part B: Effect of pH on Salivary Amylase Activity

1. Take three test tubes, each containing 5 mL of starch solution.

2. Adjust the pH of the solutions to pH 3, pH 7, and pH 9 using appropriate buffers.

3. Add 1 mL of diluted saliva to each test tube.

4. Place the test tubes at room temperature.

5. Take samples every 2 minutes and test with iodine solution to note the time required for starch digestion.

Part C: Effect of Temperature on Salivary Amylase Activity

1. Take three test tubes, each containing 5 mL of starch solution.

2. Place the test tubes in water baths set to 10°C, 37°C, and 60°C for 5 minutes.

3. Add 1 mL of diluted saliva to each test tube.

4. Keep the test tubes at their respective temperatures.

5. Take samples every 2 minutes and test with iodine solution to record the time for starch digestion.

Observations and Data:

Table 1: Digestion of Starch at Room Temperature

Table 2: Effect of pH on Starch Digestion

Table 3: Effect of Temperature on Starch Digestion

Results:

1. Salivary amylase effectively digests starch into maltose, as observed by the disappearance of the blue-black color with iodine.

2. The enzyme functions optimally at neutral pH (pH 7) and body temperature (37°C).

3. Extreme pH (acidic or alkaline) and temperatures (very low or very high) reduce the enzymatic activity, demonstrating its sensitivity.

Conclusion:

Salivary amylase is most effective at neutral pH and physiological temperature. Deviations from these conditions result in decreased enzymatic activity, illustrating the specificity and sensitivity of enzymes.

Precautions:

1. Use fresh saliva for each trial.

2. Ensure consistent concentrations of starch and saliva.

3. Conduct the experiments under controlled conditions.

4. Handle iodine with care.

PROJECT - 06

Objective - Comparative Study of the Rate of Fermentation of Wheat Flour, Gram Flour, Potato Juice, and Carrot Juice

Table of Contents

1. Introduction

2. Objective

3. Theory

4. Materials Required

5. Procedure

6. Observations and Data Analysis

7. Conclusion

8. Bibliography

1. Introduction

Fermentation is a metabolic process where microorganisms like yeast convert sugars into alcohol, carbon dioxide, or acids. This process is widely used in the production of bread, beverages, and biofuels. This project aims to study the comparative rate of fermentation of various food materials.

2. Objective

To compare the rate of fermentation of wheat flour, gram flour, potato juice, and carrot juice by observing carbon dioxide production as an indicator.

3. Theory

Fermentation occurs when microorganisms break down carbohydrates in the absence of oxygen. The rate of fermentation depends on factors such as:

• Type of carbohydrate present

• Temperature

• pH

  
  

  This study uses yeast as a fermenting agent, and carbon dioxide production is measured to determine the rate.

4. Materials Required

• Samples: Wheat flour, gram flour, potato juice, carrot juice

• Yeast

• Warm water

• Test tubes

• Beakers

• Measuring cylinders

• Balloons (to measure CO₂ production)

• Stopwatch

• Weighing balance

5. Procedure

1. Prepare yeast solution by dissolving 5 g of yeast in 50 mL of warm water. Let it activate for 10 minutes.

2. Label four test tubes as A, B, C, and D for wheat flour, gram flour, potato juice, and carrot juice, respectively.

3. Add 10 g of wheat flour to test tube A, 10 g of gram flour to test tube B, 10 mL of potato juice to test tube C, and 10 mL of carrot juice to test tube D.

4. Add 10 mL of warm water and 2 mL of yeast solution to each test tube.

5. Cover the openings of the test tubes with balloons.

6. Keep the test tubes at a constant temperature (around 37°C) for 1 hour.

7. Measure the inflation of the balloons at regular intervals (e.g., every 15 minutes).

8. Record observations.

6. Observations and Data Analysis

Data Table

7. Conclusion

1. Wheat flour showed the highest rate of fermentation, followed by potato juice, carrot juice, and gram flour.

2. The rate of fermentation is directly proportional to the type and concentration of carbohydrates available.

3. Wheat flour, rich in simple carbohydrates, produced the most carbon dioxide, indicating a faster fermentation rate.

8. Bibliography

• NCERT Chemistry Textbook

• Lab Manuals

• Online Articles: ScienceDirect, ResearchGate

PROJECT - 07

Title:

Extraction of Essential Oils from Saunf (Aniseed), Ajwain (Carum), and Illaichi (Cardamom)

Aim:

To extract essential oils present in Saunf (Aniseed), Ajwain (Carum), and Illaichi (Cardamom) and study their characteristics and uses.

Theory:

Essential oils are volatile aromatic compounds extracted from plants. They are widely used in the food, pharmaceutical, and cosmetic industries. Common extraction methods include steam distillation and cold pressing.

Properties of Essential Oils:

1. Volatile and aromatic.

2. Insoluble in water but soluble in organic solvents.

3. Have therapeutic and medicinal properties.

Sources:

• Saunf (Aniseed): Contains anethole as the primary component.

• Ajwain (Carum): Contains thymol as the main active compound.

• Illaichi (Cardamom): Contains terpinyl acetate, cineole, and other aromatic compounds.

Materials Required:

1. Saunf (Aniseed), Ajwain (Carum), and Illaichi (Cardamom) - 50 grams each.

2. Distillation apparatus.

3. Water.

4. Bunsen burner or heating mantle.

5. Separating funnel.

6. Glass beaker.

7. Organic solvent (e.g., ethanol or hexane).

8. Cotton wool.

Procedure:

1. Steam Distillation Method:

1. Grind 50 grams of each sample (Saunf, Ajwain, Illaichi) into a coarse powder to increase the surface area.

2. Place the powdered sample in the distillation flask and add water to submerge the material.

3. Set up the distillation apparatus with a condenser attached to collect the distillate.

4. Heat the flask gently to produce steam. The steam will carry the essential oil vapors.

5. The vapors condense into a liquid mixture of water and oil in the receiver.

6. Transfer the distillate into a separating funnel.

2. Separation of Essential Oil:

1. Add a small quantity of organic solvent (e.g., ethanol or hexane) to the separating funnel.

2. Shake the funnel gently and allow it to settle. The essential oil dissolves in the solvent.

3. Carefully separate the oil-solvent mixture from the aqueous layer.

4. Evaporate the solvent under reduced pressure or by gentle heating to obtain pure essential oil.

Observations:

Result:

Essential oils were successfully extracted from Saunf, Ajwain, and Illaichi using steam distillation. The oils possessed distinct aromas corresponding to their source materials.

Conclusion:

The project demonstrates the extraction of essential oils using the steam distillation method. The essential oils obtained are aromatic and have potential applications in flavoring, medicine, and aromatherapy.

Precautions:

1. Ensure the apparatus is airtight to avoid loss of volatile oils.

2. Handle organic solvents with care; avoid inhalation.

3. Maintain a consistent heat source to ensure efficient distillation.

Applications of Extracted Oils:

1. Saunf Oil: Used in flavoring and digestion-aiding medicines.

2. Ajwain Oil: Acts as an antiseptic and a digestive aid.

3. Illaichi Oil: Widely used in confectionery, perfumes, and as a carminative.

Bibliography:

1. CBSE Lab Manual for Chemistry.

2. K. Arora, Practical Chemistry.

3. Online sources on essential oil extraction methods.

PROJECT - 08

Project Title: Study of Common Food Adulterants in Fat, Oil, Butter, Sugar, Turmeric Powder, Chilli Powder, and Pepper

Objective:

The aim of this project is to identify and analyze common food adulterants in commonly used food items like fat, oil, butter, sugar, turmeric powder, chili powder, and pepper. The study also highlights the methods used to detect these adulterants and raise awareness about food safety.

Introduction:

Food adulteration is the process of deliberately adding inferior or harmful substances to food items to increase profit margins. Adulterants are substances that are either harmful or reduce the quality of food. This practice is not only illegal but also a health hazard. In this project, we will focus on identifying adulterants in seven common food items and understanding their impact on public health.

Materials Required:

1. Fat/Oil (Mustard oil, Sunflower oil)

2. Butter

3. Sugar

4. Turmeric Powder

5. Chilli Powder

6. Pepper

7. Test tubes, glass beakers, and droppers

8. Chemicals for testing: 

   • Iodine solution

   • Water (for testing)

   • Starch solution

   • Water (for testing of turmeric powder)

   • Alcohol (for detecting chili powder)

9. Bottles for storing samples

10. Pipettes and filter paper

Methodology:

1. Testing Adulterants in Fat/Oil:

• Adulterant: Argemone seeds

• Test: Take a small amount of oil and add 2-3 drops of concentrated nitric acid. If red coloration appears, argemone seeds are present.

• Observation: No color change indicates pure oil; red coloration indicates adulteration with argemone seeds.

2. Testing Adulterants in Butter:

• Adulterant: Vanaspati (Hydrogenated vegetable oil)

• Test: Heat a small portion of butter. If it melts completely and leaves behind a greasy residue, it indicates the presence of vanaspati.

• Observation: If the butter melts and leaves no residue, it is pure.

3. Testing Adulterants in Sugar:

• Adulterant: Chalk powder or washing soda

• Test: Take a sample of sugar and add a few drops of water to it. If it turns milky or forms bubbles, washing soda or chalk powder is present.

• Observation: Pure sugar dissolves easily without any reaction.

4. Testing Adulterants in Turmeric Powder:

• Adulterant: Metanil Yellow (a harmful dye)

• Test: Add a pinch of turmeric powder to a glass of water. Pure turmeric powder will leave a clear yellow color, while adulterated turmeric will show a different color or form a precipitate.

• Observation: The clear yellow color indicates pure turmeric; any turbidity or different color indicates adulteration.

5. Testing Adulterants in Chilli Powder:

• Adulterant: Brick powder or salt powder

• Test: Add a pinch of chili powder to water. If it forms a reddish solution and settles at the bottom, it is pure. If it forms a cloud or lumps, adulteration has occurred.

• Observation: Pure chili powder will dissolve in water without leaving residues.

6. Testing Adulterants in Pepper:

• Adulterant: Papaya seeds or dried blackberries

• Test: Crush the pepper and add it to a glass of water. If the water turns cloudy and a floating substance forms, it indicates adulteration.

• Observation: No floating particles indicate pure pepper.

Results and Discussion:

Conclusion:

The study successfully identified the presence of adulterants in common food items like fat, oil, butter, sugar, turmeric powder, chili powder, and pepper. The tests conducted were simple and effective in detecting common adulterants, ensuring that food safety measures are in place to prevent harmful substances from being consumed.

Suggestions for Preventing Food Adulteration:

1. Consumer Awareness: People should be educated about the harmful effects of food adulteration and be encouraged to buy food from trusted sources.

2. Strict Regulation: Government authorities should enforce stringent quality checks and penalize adulterators.

3. Use of Technology: Advanced methods such as spectroscopy can be used for more accurate detection of adulterants.

References:

1. CBSE Science Practical Manual

2. Food Safety and Standards Authority of India (FSSAI) Reports

3. Books on Food Chemistry and Safety