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INTRODUCTION

We are all familiar with the pleasant odours coming out from flowers, spices and many trees. The essence or aromas of plants are due to volatile oils present in them. These smelling volatile oils present in plants are called essential oils. Cinnamon, clove, cumin, eucalyptus, garlic, jasmine, peppermint, rose, sandalwood, spearmint, thyme, wintergreen are a few familiar examples of valuable essential oils. The term “essential oils” literally means “oils derived from the essence” of plants.

Essential oils are mainly used for their pleasant odours and flavours in perfumes and as flavouring agents in foods. Some are used in medicines (e.g., camphor, wintergreen, eucalyptus) others as insect repellents (e.g., citronella). Chemically essential oils are composed of complex mixtures of ester, alcohols, phenols, aldehydes, ketones and hydrocarbons. They are essentially non-polar compounds and are thus soluble in non-polar solvents such as petroleum ether, benzene etc. Essential oils may occur in all parts of the plant, but they are often concentrated in the seeds or flowers. They are obtained from the plants by the process of steam distillation and extraction. The technique of steam distillation permits the separation of volatile components from non-volatile materials without raising the temperature of the distillation above 100° C.

Thus steam distillation reduces the risk of decomposition of essential oils.

ANISEED ESSENTIAL OIL

Aniseed Plant

Aniseed, on steam distillation, yields an essential oil, known as Oil of Aniseed`, which has now replaced the fruits for medicinal and flavouring purposes. Aniseed oil is a colourless or pale-yellow liquid having the characteristic odour and taste of the fruit.
The yield of oil generally varies from 1.9 to 3.1 per cent. Higher values up to 6 per cent have been reported from Syrian aniseed. Crushing of fruits prior to distillation gives better yields of oil. The material should be distilled soon after the crushing to prevent any loss of oil due to evaporation. Aniseed oil is a highly refractive liquid, which solidifies on cooling. The congealing point depends much on the anethole content and is a valuable criterion for evaluating the oil. Exposure of the oil to air causes polymerization, and some oxidation also takes place with the formation of anisaldehyde and anisic acid.

The chief constituent of aniseed oil is anethole, which is present to the extent of 80 to 90 per cent and is mainly responsible for the characteristic flavour of the oil. The oil also contains methyl chavicol, p-methoxyphenyl acetone, and small amount of terpenes and sulphur containing compounds of disagreeable odour.

Aniseed Essential Oil

Common Method of Extraction:- Steam Distillation

Color:- Clear

Botanical Name:- Pimpinella anisum

Aromatic Description:- Distinctive scent of licorice. Rich and sweet.

Constituents:- a-pinene, camphene, B-pinene, linalool, cis-anethole, trans-anethole, safrole, anisaldehyde, acetoanisole.

Uses of Aniseed Oil:-

• Ø In aromatherapy, aniseed essential oil is used to treat colds and flu.
• Ø Aniseed oil can be made into a liquid scent and is used for both hunting and fishing. It is put on fishing lures to attract fish.
• Ø Anethole, the principal component of anise oil, is a precursor that can eventually produce 2,5-dimethoxybenzaldehyde which is can be used in the clandestine synthesis of psychedelic drugs such as 2C-B, 2C-I and DOB.
• Ø Oil of aniseed is also reported to be used as an aromatic carminative to relieve flatulence, and as an ingredient of cough lozenges in combination with liquorice.
• Ø Essential oil is also used externally as an insecticide against small insects such as head lice, mites and vermin. It also has fungicidal properties.

EXPERIMENT

REQUIREMENTS:-

Steam generator (Copper Vessel), round bottom flask (500 ml), conical flask, condenser, glass tubes, iron stand, sand bath, separatory funnel, tripod stands, burners, Ajwain(Carum), Petroleum ether(60-80°C), Saunf(Aniseed) .

PROCEDURE:-

1. Set the apparatus as shown in the picture of Experimental Setup. The apparatus consists of a steam generator connected to the round bottom flask through a glass inlet tube. The flask is connected to a water condenser through a glass outlet tube. Condenser is further attached to a receiver through an adaptor.
2. Take about 750 ml of water in the steam generator and start heating to produce steam.
3. In the round bottom flask take about 75 gm of crushed saunf.
4. A vigorous current of steam from steam generator is passed through the round bottom flask.
5. A part of the steam condenses in the round bottom flask. As more and more steam is passed, the steam volatile components of saunf pass through the condenser along with steam. These contents on condensation are collected in the receiver.
6. The contents in the round bottom flask may be heated by a Bunsen burner to prevent excessive condensation of steam.
7. The process of steam distillation is continued for about half an hour.
8. Transfer the distillate to a separating funnel and extract with 20 ml portions of petroleum ether 3 times.
9. Combine the petroleum ether extracts in a 250 ml conical flask and dry it with the help of anhydrous sodium sulphate.
10. Remove the solvent from the dried filtrate by careful distillation in a water bath. The essential oil is left behind in the distillation flask.
11. Find the weight of the extracted essential oil. Note the colour, odour and weight of the essential oil.

OBSERVATIONS:-

1.) Saunf (Aniseed):-

Weight of Saunf taken        = 100 gm

Initial Weight of the bottle = 10gm(x)

Weight of bottle + essential oil = 11.25 gm(y)

Weight of essential oil extracted =(y-x) =1.25 gm

Percentage of essential oil = (y/100)*100=1.25 %

Colour of the oil    = Colourless

Odour of the oil = Saunf like smell.

2.) Ajwain (Carum):-

Weight of Saunf taken        = 75 gm

Initial Weight of the bottle = 10 gm(x)

Weight of bottle + essential oil = 11 gm(y)

Weight of essential oil extracted =(y-x) =1 gm

Percentage of essential oil = (y/75)*100=1.33%

Colour of the oil    = Colourless

Odour of the oil = Ajwain like smell.

BIBLIOGRAPHY

• Comprehensive Chemistry Practical Class-XII.
• http://www.essentialoils.co.za/essential-oils/aniseed.htm

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Objective:

The goal of this project is to measure the solubilities of some common chemicals:

• Table salt (NaCl)
• Epsom salts (MgSO₄)
• sugar (sucrose, C₁₂H₂₂O₁₁).

Introduction

A good part of the substances we deal with in daily life, such as milk, gasoline, shampoo, wood, steel and air are mixtures. When the mixture is homogenous, that is to say, when its components are intermingled evenly, it is called a solution. There are various types of solutions, and these can be categorized by state (gas, liquid, or solid).

The chart below gives some examples of solutions in different states. Many essential chemical reactions and natural processes occur in liquid solutions, particularly those containing water (aqueous solutions) because so many things dissolve in water. In fact, water is sometimes referred to as the universal solvent. The electrical charges in water molecules help dissolve different kinds of substances. Solutions form when the force of attraction between solute and solvent is greater than the force of attraction between the particles in the solute.

Two examples of such important processes are the uptake of nutrients by plants, and the chemical weathering of minerals. Chemical weathering begins to take place when carbon dioxide in the air dissolves in rainwater. A solution called carbonic acid is formed. The process is then completed as the acidic water seeps into rocks and dissolves underground limestone deposits.
Sometimes, the dissolving of soluble minerals in rocks can even lead to the formation of caves.

If one takes a moment to consider aqueous solutions, one quickly observes that they exhibit many interesting properties. For example, the tap water in your kitchen sink does not freeze at exactly 0°C. This is because tap water is not pure water; it contains dissolved solutes. Some tap water, commonly known as hard water, contains mineral solutes such as calcium carbonate, magnesium sulphate, calcium chloride, and iron sulphate. Another interesting solution property is exhibited with salt and ice.

Another example comes from the fact that salt is spread on ice collected on roads in winters. When the ice begins to melt, the salt dissolves in the water and forms salt water. The reason is that with the addition of salt the melting point of water increases and as a result the snow melts away faster.

Even some organisms have evolved to survive freezing water temperatures with natural “antifreeze.” Certain arctic fish have blood containing a high concentration of a specific protein. This protein behaves like a solute in a solution and lowers the freezing point of the blood. Going to the other end of the spectrum, one can also observe that the boiling point of a solution is affected by the addition of a solute. These two properties, namely freezing-point depression and boiling-point elevation, are called colligative properties (properties that depend on the number of molecules, but not on their chemical nature).

Basic Concepts

A saturated solution is a mixture in which no more solute can be practically dissolved in a solvent at a given temperature. It is said practical because theoretically infinite amount of solute can be added to a solvent, but after a certain limit the earlier dissolved solute particles start rearranging and come out at a constant rate. Hence overall it appears that no solute is dissolved after a given amount of solute is dissolved. This is known as a saturated solution.

In an unsaturated solution, if solute is dissolved in a solvent the solute particles dissociate and mix with the solvent without the re-arrangement of earlier dissolved solute particles.

Solubility depends on various factors like the K_sp of the salt, bond strength between the cation and anion, covalency of the bond, extent of inter and intramolecular hydrogen bonding, polarity, dipole moment etc. Out of these the concepts of H-bonding, covalency , ionic bond strength and polarity play a major role if water is taken as a solvent.

Also physical conditions like temperature and pressure also play very important roles as they affect the kinetic energy of the molecules.

Materials and Equipment

To do this experiment following materials and equipment are required:

• Distilled water
• Metric liquid measuring cup (or graduated cylinder)
• Three clean glass jars or beakers
• Non-iodized table salt (NaCl)
• Epsom salts (MgSO₄)
• Sugar (sucrose, C₁₂H₂₂O₁₁)
• Disposable plastic spoons
• Thermometer
• Three shallow plates or saucers
• Oven
• Electronic kitchen balance (accurate to 0.1 g)

Experimental Procedure

Determining Solubility

1. Measure 100 mL of distilled water and pour into a clean, empty beaker or jar.

2. Use the kitchen balance to weigh out the suggested amount (see below) of the solute to be tested.

a.   50 g Non-iodized table salt (NaCl)

b.    50 g Epsom salts (MgSO4)

c.   250 g Sugar (sucrose, C₁₂H₂₂O₁₁)

3. Add a small amount of the solute to the water and stir with a clean disposable spoon until dissolved.

4. Repeat this process, always adding a small amount until the solute will no longer dissolve.

5. Weigh the amount of solute remaining to determine how much was added to the solution.

6. Try and add more solute at the same temperature and observe changes if any.

7. Now heat the solutions and add more solute to the solutions.

Observations:

Adding more solute at the same temperature to the saturated solutions yielded no significant changes in NaCl and Epsom salt. However, at all temperatures the saturation point of sucrose could not be obtained exactly as due to the large size of the molecule the solution became thick and refraction was more prominent. Neglecting this observation in the room for error, the experiments agreed with the theory.

Adding more solute to heated solutions increased the solubility in all the 3 cases. The largest increase was shown by NaCl, followed by Epsom salt and sucrose. These facts too agreed with the theory as at high temperatures the kinetic energy of molecules increases and the collisions are more effective.

Conclusions:

The solubility of NaCl is the highest as it an ionic salt and easily dissociates in water. Also since the size of both the cation and

anion are small, the collisions are more and hence the probability of dissociation is high. The solubility of MgSO₄ is also high as it is also an ionic salt, but due to a larger anion, collisions are not

very effective. The solubility of C₁₂H₂₂O₁₁ is the least as it a very large molecule due to which hydrogen bonding with the water

molecules is not very effective. Also due to the large number of carbon and oxygen atoms, inter molecular H-bonding is more dominant than intramolecular H-bonding.

Precautions:

1. While adding the solute to the solvent, the solution should be stirred slowly so as to avoid the formation of any globules.
2. Stirring should not be vigorous as the kinetic energy of the molecules might change due to which solubility can increase.
3. While stirring, contact with the walls of the container should be avoided as with every collision, an impulse is generated which makes the dissolved solute particles rearrange themselves. As a result solubility can decrease.
4. The temperature while conducting all the three experiments should be approximately same.
5. Epsom salt should be first dried in order to remove the water of crystallization (MgSO₄.7H₂O).

BIBLIOGRAPHY

• NCERT CHEMISTRY XII
• ENCARTA ENCYCLOPEDIA 2009

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Bio diesel

INTRODUCTION

Green chemistry is the branch of chemistry concerned with developing processes and products to reduce or eliminate hazardous substances. One of the goals of green chemistry is to prevent pollution at its source, as opposed to dealing with pollution after it has occurred.

Principles of Green Chemistry

Prevention

It is better to prevent waste than to treat or clean up waste after it has been created.

Atom Economy

Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.

Less Hazardous Chemical Syntheses

Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

Designing Safer Chemicals

Chemical products should be designed to effect their desired function while minimizing their toxicity.

Safer Solvents and Auxiliaries

The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.

Design for Energy Efficiency

Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure.

Use of Renewable Feed stocks

A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.

Reduce Derivatives

Unnecessary derivatization (use of blocking groups, protection, temporary modification of physical/chemical processes) should be minimized or avoided if possible because such steps require additional reagents and can generate waste.

Catalysis

Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.

Design for Degradation

Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.

1. Real-time analysis of Pollution Prevention

Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.

1. Inherently Safer Chemistry for Accident Prevention

Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fires.

Bio-diesel is an eco-friendly, alternative diesel fuel prepared from domestic renewable resources i.e. vegetable oils (edible or non- edible oil) and animal fats. These natural oils and fats are made up mainly of triglycerides. These triglycerides when raw striking similarity to petroleum derived diesel and are called “Bio-diesel”. As India is deficient in edible oils, non-edible oil may be material of choice for producing bio diesel . For this purpose Jatropha curcas considered as most potential source for it. Bio diesel is produced by transesterification of oil obtains from the plant. Jatropha Curcas has been identified for India as the most suitable Tree Borne Oilseed (TBO) for production of bio-diesel both in view of the non-edible oil available from it and its presence throughout the country. The capacity of Jatropha Curcas to rehabilitate degraded or dry lands, from which the poor mostly derive their sustenance, by improving land’s water retention capacity, makes it additionally suitable for up-gradation of land resources. Presently, in some Indian villages, farmers are extracting oil from Jatropha and after settling and decanting it they are mixing the filtered oil with diesel fuel. Although, so far the farmers have not observed any damage to their machinery, yet this remains to be tested and PCRA is working on it. The fact remains that this oil needs to be converted to bio-diesel through a chemical reaction – trans-esterification. This reaction is relatively simple and does not require any exotic material. IOC (R&D) has been using a laboratory scale plant of 100 kg/day capacity for trans-esterification; designing of larger capacity plants is in the offing. These large plants are useful for centralized production of bio-diesel. Production of bio-diesel in smaller plants of capacity e.g. 5 to 20 kg/day may also be started at decentralized level.

REQUIREMENT

1. Eye protection
2. Access to a top pan balance
3. One 250 cm³ conical flask
4. Two 100 cm³ beakers
5. One 100 cm³ measuring cylinder
6. Five plastic teat pipettes
7. Distilled or deionised water
8. 100 cm³ vegetable-based cooking oil
9. 15 cm³ methanol (highly flammable, toxic by inhalation, if swallowed, and by skin absorption)
10. 1 cm³ potassium hydroxide solution 50% (corrosive).

EXPERIMENT 1

1. Measure 100 cm³ of vegetable oil into the 250 cm³ flask. Weigh the flask before and after to determine the mass of oil you used.
2. Carefully add 15 cm³ of methanol.
3. Slowly add 1 cm³ of 50% potassium hydroxide.
4. Stir or swirl the mixture for 10 minutes.
5. Allow the mixture to stand until it separates into two layers.
6. Carefully remove the top layer (this is impure biodiesel) using a teat pipette.
7. Wash the product by shaking it with 10 cm³ of distilled or deionised  water.
8. Allow the mixture to stand until it separates into two layers.
9. Carefully remove the top layer of biodiesel using a teat pipette.
10. Weigh the amount of biodiesel you have collected and compare it to the amount of vegetable oil you started with.

REQUIREMENT

• Eye protection
• Small glass funnel (approximately 7 cm diameter)
• One 250 cm³ flask
• Two boiling tubes
• One two-hole stopper to fit the boiling tubes
• Filter pump
• A piece of wide bore glass tubing approximately 10 cm long with two one-hole stoppers to fit
• A piece of vacuum tubing approximately 35 cm long
• Two short pieces of glass tubing to fit the one-hole stoppers
• 5 cm glass bend to fit the two-hole stopper
• 90^o glass bend to fit the two-hole stopper (one leg to extend to bottom of flask)
• Two stands and clamps
• Two small metal sample dishes
• A little sodium hydroxide solution 0.1 mol dm^-3 (irritant)

EXPERIMENT 2

1. Pour 125 cm³ of distilled water into the 250 cm³ flask and add 10 cm³ of universal indicator. Add one drop of 0.1 mol dm^-3 sodium hydroxide solution and gently swirl the flask so that the colour of the solution is violet or at the most basic end of the universal indicator colour range.
2. Place 10 cm³ of this solution into the boiling tube.
3. Assemble the apparatus illustrated in Figure 1, attaching it to the filter pump with the vacuum tubing.
4. Place 2 cm³ of biodiesel onto a wad of mineral wool in the metal sample cup.
5. Turn on the water tap so the filter pump pulls air through the flask and ignite the biodiesel. Position the funnel directly over the burning fuel, so as to capture the fumes from the burning fuel.  Mark or note the position of the tap handle so you can run the pump at the same flow rate later in the experiment.
6. Allow the experiment to run until the universal indicator turns yellow and time how long this takes.
7. Record what happens in the funnel and in the glass tube containing the second piece of mineral wool.

PRECAUTION

• Wear eye protection.
• Methanol is flammable and poisonous.
• Potassium hydroxide is corrosive.
• Take care if you have to insert glass tubing into the stoppers yourself. Make sure that your teacher shows you the correct technique.

BIBLIOGRAPHY

www.chemistry.org

www.ott.doe.gov/biofuels/environment.html

www.pcra.org

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INTRODUCTION

In the past decade there has been a tremendous increase in the yields of various crops to meet the demand of overgrowing population, achieved by using pesticides and insecticides. These are chemicals that are sprayed over crop to protect it from pests. For example, DDT, BHC, zinc phosphide, Mercuric chloride, dinitrophenol, etc. All pesticides are poisonous chemicals and are used in small quantities with care. Pesticides are proven to be effective against variety of insects, weeds and fungi and are respectively called insecticides, herbicides and fungicides. Most of the pesticides are non-biodegradable and remain penetrated as such into plants, fruits and vegetables . From plants they transfer to animals , birds and human beings who eat these polluted fruits and vegetables. Inside the body they get accumulated and cause serious health problems. These days preference is given to biodegradable insecticides like malathion. The presence of Insecticides residues in even raw samples of wheat, fish, meat , butter etc. have aroused the concern of agricultural administrators, scientists and health officials all over the world to put a check over the use of insecticides and to search for non insecticidal means of pest control.

EXPERIMENT

AIM

To study the presence of insecticides or pesticides (nitrogen containing) in various fruits and vegetables.

MATERIALS REQUIRED

Mortar and pestle , beakers, funnel , glass rod , filter paper china dish , water bath, tripod stand, fusion tube, knife, test tube.

Samples of various fruits and vegetables, alcohol, sodium metal, ferric chloride, ferrous sulphate crystals, distilled water and dil. Sulphuric acid.

PROCEDURE

Take different types of fruits and vegetables and cut them into small pieces separately.

Transfer the cut pieces of various fruits and vegetables into it separately and crush them .

Take different kinds for each kind of fruits and vegetables and place the crushed fruits and vegetables in these beakers and add 100 ml of alcohol to each of these . Stir well and filter.

Collect the filtrate in separate china dishes, Evaporate the alcohol by heating the china dishes one by one over a water bath and let the residue dry in the oven .

Heat a small piece of sodium in a fusion tube , till it melts. Then add one of the above residues from the china dish to this fusion tube and heat it till red hot.

Drop the hot fusion tube in a china dish containing about 10 ml of distilled water. Break the tube and boil the contents of the china dish for about 5 minutes . Cool and filter the solution. Collect the filtrate .

To the filtrate add 1 ml of freshly prepared ferrous sulphate solution and warm the contents.

Then add 2-3 drops of ferric chloride solution and acidify with dilute HCl.

If a blue or green ppt. or colouration is obtained it indicates the presence of nitrogen containing insecticides.

Repeat the test of nitrogen for residues obtained from other fruits and vegetables and record the observation.

OBSERVATIONS

BIBLIOGRAPHY

1. Modern’s ABC of practical chemistry-XII
2. Comprehensive practical chemistry – XII
3. NCERT chemistry -XII

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