Chemistry Notes Info - Notes for 9, 10, 11, 12, BSc, MSc, Science Quiz, Chemistry GK, Infographics: MSc Chemistry Notes

Charge Transfer Transition

CHARGE TRANSFER SPECTRA

Definition of charge transfer Transition by- www.ChemistryNotesInfo.com All electronic transition that occur between orbitals that are centered on different atoms is known as charge transfer Transition. It's absorption band is very strong Types of charge transfer bands Two types of charge transfer bands seen in metal complexes. i.e. 1: Legand to Metal charge transfer bands. 2: Metal to Legand charge transfer bands... read more at http://chemistrynotesinfo.blogspot.in/2014/12/charge-transfer-transition.html

Definition of charge transfer Transition

All electronic transition that occur between orbitals that are centered on different atoms is known as charge transfer Transition.
It's absorption band is very strong

Types of charge transfer bands

Two types of charge transfer bands seen in metal complexes. i.e.
1: Legand to Metal charge transfer bands.
2: Metal to Legand charge transfer bands.

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Extraction of Essential Oil by Steam Distillation of Tulsi (Ocimum Basillicum)

Extraction of Essential Oil by Steam Distillation of Tulsi (Ocimum Basillicum)

Essential oils are insoluble in water and evaporate easily. We can obtain essential oil from plant tissues by distillation or extraction processes. Generally essential oils are obtain from every part of plant like stem, root, leaves, flowers, seed, branches etc. And these essential oils are used in the preparation of drugs, cosmetics and perfumes.
Holi Tulsi Plant
Ocimum Basillicum means Tulsi is an aromatic plant. Ocimum Basillicum is used to obtain essential oil useful for different application. This oil evaporates within 24 hours after applying it to our body. This essential oil helps in cure of digestion problem, strained muscles, headaches and nervous breakdowns. Due to its good medicinal properties and aroma its demand is very high in many countries. A person or company can build a small or large scale industry for the extraction of essential oil from Ocimum Basillicum (Tulsi).

Top 10 General qualitative properties of Ocimum Basillicum essential oil are given below-

essential oil extraction equipment photo1.  Appearance : Transparent fluid
2.  Color : Pale yellow
3.  Fragrance : Ocimum Basillicum’s distinctive flavor and fragrance
4.  Refractive Index on 20°C : 1.51200 to1.51900
5.  Specific Gravity on 25°C : 0.95200 to 0.97300
6.  Optical gyration on 25°C : [-] 8.85º to [-] 11.85º
7.  Well mixed with Hydroxycitronellal
8.  Insoluble in water
9.  Dissolved in paraffin oil

How to obtain oil from holi Tulsi plant?

The extraction of essential oil by steam distillation of ocimum basillicum (Tulsi) is a solid-liquid extraction process. This process completes in following steps-
Flow diagram of steam distilatillation
1.  Collect plant material and dry it if required.
2.  Fill this plant material in distillation vessel.
3.  Add water or solvent (like Ethanol, n-Hexane) in distillation vessel.
4.  Heat the mixture in well-equipped distillation vessel in control environment and controlled temperature, then
5.  Diffusion of essential oil from inside of solid material of plant to its surface occurs, then
6.  Transfer of mass from surface of plant solid material to surrounding liquid occurs, then
7.  This liquid contains essential oil which is obtained by reverse cooler.
8.  Then the collection of above liquid obtained from reverse cooler is put to stand for some time then essential oil come over water, then
9.  We perform layer separation to separate out essential oil from water, then
10.              Store this essential oil in dark, closed vessel for future use.
how to obtain Essential oil by steam distillation ?
The experimental results proves that yield of essential oil of Tulsi (Ocimum-Basillicum)  from only leaves of plant is slightly higher than from the mixture of leaves and stems (means plant crush).

BSc1Year Mathematical Concepts

BSc 1st Year Mathematical Concepts

Mathematics For Chemist

Mathematics for chemist or general mathematics needed in chemistry include chapter of basic mathematics of upto class 10 and some chapters of higher classes like Vectors, Matrices and Linear Algebra, Differential Equations, Differenciation, Intigration, Group Theory.
maths for chemistry
Maths For Chemist

Vector

Vector is a quantity having magnitude and direction. example- Force, Weight etc.

Matrices

Its singular form is Matrix, It is a rectangular array of numbers or symbols and these numbers and symbols are arranged in rows and columns and one can perform operation on it as per defined rules to solve matrices.

Linear Algebra

Linear Algebra is a mathematical tool to define any thing in 2D ( Two Dimensional) but may be extended to 3D, 4D,5D..... so on as per requirement.

Differential Equations

Differential Equations is an mathematical equation which involvs derivatives of a function or functions.

Differenciation

Differenciation is process or action of differentiating.

Intigration

Intigration is process or action of intigrating.

Group Theory

Group Theory is a tool to analyse any thing or system which have symmetry and posseses symmetry element.

Vitexin - MSc Chemistry: Subject- Chemistry of Natural Products

VITEXIN

Vitexin is a naturally occuring compound of FLAVONOID family and also known as Apigenin Flavone Glucoside or Apigenin-8-C-glucoside. Vitexin have Molecular weight of about 432.38 gm/mole with molecular formula C21H20O10.
 Vitexin (Apigenin Flavone Glucoside or Apigenin-8-C-glucoside ) is obtained from Passion flower, Chaste tree and also present in Phyllostachys Nigra Bamboo Leaves and also found in many other plant or special parts of plants. Vitexin inhibits Thyroid Peroxidase enzyme. Other similar compound like vitexin is Isovitexin which is apigenin-6-C-glucoside while vitexin is apigenin-8-C-glucoside. Vitexin should be stored in desiccator.

BSc2Year Electromagnetic spectrum UV and Visible spectroscopy

Spectroscopy

                 It is a branch of science which deals with the study of interaction of matter with electromagnetic radiation.

Electromagnetic Radiation 

Electromagnetic Radiations are a certain amount of energy depending upon its wavelength. Hence these radiations are the sources of energy so called as electromagnetic energy or radiant energy.
Electromagnetic Radiations are of many types like radio waves, UV rays, IR rays, visible light etc. these are all electromagnetic radiations with different energy, wavelength and frequency. All types of electromagnetic radiations travel with the speed of light but differ in wavelength and frequency.
Energy of electromagnetic radiations can be expressed as
                       
Where E = Energy
            n = Frequency
            l = Wavelength
            c = Velocity of light = 3*108 m/s.
            h = planks constant

            Types of electromagnetic radiations

Type
Frequency (Hz)
Wavelength (1/m)
Radio wave (low energy)
3*105
103
Microwave
3*109
10-1
Infrared
3*1010
10-2
Visible light
3*1014
10-6
Ultraviolet
3*1016
10-8
X-rays
3*1018
10-10
Gamma rays (high energy)
>3*1018
<10-10

Type of spectra : 

                      Spectra are of two types

1.     Emission spectra :  

                             When a substance is exposed to intense heat or light its atoms or molecules absorbs energy and get excited. When these atoms or molecules return to their initial state they emit radiations which when pass through a prism it produce a spectrum. This spectrum is known as a emission spectrum. When this type of spectrum is recorded on a photographic plate then bright lines are formed on a black background in case of atoms and bands are formed in case molecules

2.     Absorption Spectra : 

                                 When a substance or matter is exposed to intense heat or light it absorbs energy. Due to this intensity of absorption varies as function of the frequency. This variation is known as absorption spectrum. This type of spectra contains dark (black) lines or bands on light coloured background as some radiations are absorbed by the medium.
In this process only those photons of radiation are absorbed whose energy is equal to energy difference (DE) between two energy levels of molecules of substance.
                                   
Where h = planck’s constant = 6.63 * 10-34 Js
            n = Frequency
            c = Velocity of light = 3 * 108 m/s
            l = Wavelength of radiation
            NA = Avogadro’s number = 6.02 * 1023 mol-1

Difference between Emission and Absorption Spectrum : 

                                                                                   In Emission Spectrum molecules come back to lower energy state from higher energy state while in Absorption Spectrum The molecule goes to Higher energy state from lower energy state.

Absorption Spectrum and its types : 

                                                      In addition to the nuclear energy, total internal energy of a molecule consist of three types of energies.
                                    Einternal = Eelectronic + Evibrational + Erotational
Since, electromagnetic radiation is a form of energy so its absorption by a molecule, increases the internal energy of the molecule. Also when a molecule is exposed to electromagnetic radiation, molecule does not absorbs all the radiations rather it absorb a particular portion of radiation depending upon the structure of the molecule and amount of absorption of energy depend upon the frequency of the radiation also. So it is clear that different molecules absorb different type of energies and undergo different excitations. Depending upon the absorption of energy molecule may go under Electronic excitation, Vibrational excitation and/or Rotational excitation. So produces different Spectra.

Table : Some Components of the Electromagnetic Radiation and Absorption Spectra
Absorbed Radiation and Type of Spectra
Wavelength
Energy
(kJ/mol)
Types of Excitation
Effect on Molecule
Application
Microwave
1 cm
0.01 - 1
Rotational
Changes in the Rotational energy levels of the molecule
Calculation of bond distance and bond length
Infrared
2 – 15 mm
1 – 100
Vibrational and Rotational
Changes in Vibrational and rotational energy levels
Identification of functional groups, Calculation of Bond length, Bond angle and Qualitative analysis
Electronic
(i)                Visible





(ii)              Ultraviolet

200-400 nm





400-800 nm

150-300





300-600

Electronic





Vibrational and rotational transitions also take place but their resolution is not measurable

Change in Electronic energy level




Qualitative and quantitative analysis


The Absorption energy is measured with the help of Spectrophotometer and expressed as Frequency, Wavelength or Wave-number.
                       

Law of Light Absorbance :  

                                        According to the Lambert Beer’s Law “The Absorption of light is directly proportional to the concentration of the solution and the length of the cell containing sample.
                                   
                                      
Where, I0 = Intensity of incident Radiation
            I  = Intensity of transmitted radiation
            c = Molar concentration
            l = Length of the cell in centimetre
            e(epcylon) = Molecular extinction coefficient
 The Wavelength at which molecule has maximum Absorption coefficient e (max) is expressed as l (max). in above expression log I0/I is known as absorbance or optical density of the solution. And log I/I­0 is known as Transmission of the solution.

Ultraviolet and Visible Spectroscopy

It is a type of Absorption Spectroscopy in which Electromagnetic Radiation of UV region (l = 200 – 400 nm) or visible region (l = 400 – 800 nm) when passed through a sample containing a multiple bond, a part of incident radiation is absorbed by the sample (compound). Amount of absorbed Radiation Energy depends upon Wavelength of radiation and nature of the sample (compound). The absorbed radiation excites electron from lower energy level to higher energy level so electrons transferred from bonding orbital to the anti-bonding orbital. The amount of absorbed radiation is measured with spectrophotometer.

Spectrophotometer

                           Tungsten filament Lamp and hydrogen discharge lamp are used as source of light (energy) for visible and Ultraviolet region respectively. Sample is hold in a cell, generally cell is placed between slit of spectrophotometer.
                       
And                   

Chromohore :  

                       Those isolated groups which exhibit characteristic absorption in UV region. So these group Absorb UV radiation and known as chromophores. Generally they are covalently unsaturated groups (contains double bonds).
Actually, those functional groups that involve n-π* and π-π* transitions are known as chromophores.

Auxochrome : 

                    An auxiliary group which shifts absorption band towards longer wavelength is known as auxochrome. Auxochrome is a saturated group having non-bonding or n-electrons which when attached to chromophore changes both the intensity of bond and absorption maxima.
Some of the shifts in absorption maxima have characteristic names like

1.     Bathochromic shift : 

                                     The shifting of absorption bands towards the longer wavelength is known as Bathochromic shift. It is also known as Red shift.

2.     Hypsochromic shift : 

                                     The shifting of absorption bands towards the shorter wavelength is known as Hypsochromic shift. It is also known as blue shift.

3.     Hyperchromic shift : 

                                    If the presence of a group increases the intensity of the intensity of the band. It is known as hyperchromic shift.

4.     Hypochromic shift : 

                                    If the presence of a group decreases the intensity of the intensity of the band. It is known as hypochromic shift.

Application of ultraviolet spectroscopy

1.     Identification of a compound :  

                                                 The absorption spectra of a compound is its characteristic property. Value of l max  at which maximum absorption take place is note same for two compounds i.e. every compound have a particular wavelength at which maximum absorption takes place. This property is used to identify a compound. So a spectrum of unknown compound is compared with standard spectra to identify a compound.

2.     Identification of geometrical isomers :  

                                                               cis and trans isomer are differentiated by the study of UV spectrum. In trans isomer π-π* transition take place at the higher wavelength while in cis isomer it take place at lower wavelength.  

3.     Calculating molecular weight of a compound : 

                                                                           Prepare 1% solution of organic compound and fill it in 1 cm thick cell and determine its absorbance. Suppose A is absorbance, M is molecular weight then molar concentration is c = 10/M, cell length l = 1 cm. According to Lambert-Beer’s law-
A = ecl
A = e * (10/M) * 1
M = 10e/A

4.     Study of reaction kinetics : 

                                             Study of reaction kinetics can be made by studying the absorption spectrum of products and reactants time to time. As l max for product and reactant is different so their concentration can be measured at any stage of the reaction.

5.     Functional group Analysis : 

                                             UV Spectroscopy is used in identification of some functional groups.

6.     Ascertaining of purity :  

                                        Every compound have a particular Spectrum if additional bands are found then given compound is impure (on comparison with standard Spectrum).

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