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ELECTRICAL MEASURING INSTRUMENTS For the detection or measurement of electric current, potential difference, and resistance certain instruments have been devised viz. The galvanometer for the detection of small currents measurements of small currents of the order of micro amperes or mili amperes the voltmeter or potentiometer for the measurement of potential difference (and voltage) between two points of a circuit are the EMF of a source the ammeter for the measurement of large currents the wheatstone bridge the meter Bridge the post office box and the ohmmeter for the measurement of resistance. THE MOVING COIL GALVANOMETER The moving coil galvanometer is a basic electrical instrument it is used for the detection (and Measurement) of small currents. Its underlying principle is the fact that when a current flows in a rectangular coil placed in a magnetic field it experiences a magnetic torque. If it is free to rotate under a controlling torque, it rotates through an angle proportional t...
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LEAD PIGMENT Lead forms various types of pigments which are used to give the proper color to paints etc.Some of them are described below: White Lead pigment Red Lead Pigment Chrome Yellow Pigment Chrome Red Pigment Turner's Yellow Pigment (i) White Lead Pigment : It is a basic lead carbonate and has approximately composition as [ 2PbCO3.Pb(OH)2] or [Pb3.(CO3)2] Preparation : Chamber Process or Duch Process : When a mixture of the vapours of acetic acid and steam is passed into the chambers containing lead sheets (buckets) about 2-3 days,until the corrosion of lead is complete.By passing the mixture of CO2 and vapours of acetic acid through this corroded lead for about 3-4 weeks,the White Lead is formed on the surface of lead sheets.This product is then scratched,dried and packed. 2Pb +2CH3COOH + 2H20 ---------> [Pb(OH)2.Pb(CH3COO)2] + 2H2 3[Pb(OH).Pb(CH3COO)2] + 2H2O + 2CO2 -------------> 2[2PbCO3.Pb(OH)2] + 6CH3COOH A better "White Lead" is obtained by passing CO2 ...
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TYPES OF ELEMENTS BASED ON ELECTRONIC CONFIGURATION The periodic table has been divided into s,p,d and f blocks on the basis of electronic configuration : (1) The Noble Gases : In the periodic table, the  noble gases are found at the end of each period in zero group.They are colorless gases up to some extent chemically non reactive and diamagnetic. The electronic arrangement of ns2,np6 is exceptionally stable.Discontinuities in energy level diagram occur after these configurations are attained.With the exception of helium (Z=2) all the noble gases have outer electronic configuration of 2s2,2p6 no atom has a complete outer shell with exception of helium and noble gases. (2) Representative elements of typical elements : All elements of sub-groups of the periodic table are representative of typical elements.They include metals ,non metals and metalloids.Some of the elements are paramagnetic and some are diamagnetic.These include of elements of s and p-blocks. (a) s-block elements : In...
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ISOTOPES OF HYDROGEN The existence of hydrogen of elements was first discovered by J.J. Thomson in 1912-1913 while working on the properties of neon.The isotopes may be defined as  "Atoms of the same elements having same atomic number but different mass numbers" It may also be defined as "Atoms that have the same number of protons but different number of neutrons in their respective nuclei" Nearly all elements found in nature are mixture of several isotopes.Isotopes of hydrogen are given special names while isotopes of other elements are not given any special name. There are 3 isotopes of hydrogen, mainly: Protium Deuterium Tritium (i) Protium  It is also known as ordinary Hydrogen.It contains one proton in the nucleus and there is one electron in 1s orbital (First Shell). It has atomic number one and atomic mass number is also 1 . Naturally free occuring hydrogen or in the form of compounds contain about 99.98% protium. (ii)Deuterium  It is also called heavy hyd...
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DIGESTION OF FOOD The food of animals and men consists of complex organic substances such as carbohydrate, fats, proteins etc. Theses substances as such cannot be absorbed by cells hence it is necessary that our body mechanism must change these complex molecules into simple absorbable by cells hence it is necessary that our body mechanism must change these complex molecules into simple absorbable form. DIGESTION : It is the process of breaking down of food mechanically and chemically into simple water soluble units, suitable of being absorbed into the body fluids.             In man digestion and absorption of food occur in the alimentary canal which is about 9 meter long.The digestion is extracellular within the gut cavity and mainly is the enzymatic hydrolysis of food.            Different parts of alimentary canal perform their specific action in digestion as follows: (a) DIGESTION IN MOUTH (BUCCAL DIGESTION):-  The di...
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FOOD AND NUTRITION  Introduction : Food and nutrition is a field of biochemistry which deals with the nutrients and caloric requirement of the living body.It deals with the effect on growth and metabolism of the living system arising from the imbalanced diet.For instance the statistical survey data of food and nutrition showed that 30 % population was suffering from the disease of malnutrition Diseases like decayed and crocked teeth, bone deformation,lack of mental alertness and under weight were real outcome of the unbalanced food and diet. Classification : The food is required by the body to achieve three purposes.  (a) Energy  (b) Growth and maintenance of tissues  (c) Regulation of body processes and for the sake of simplicity It is classified into six groups:   (i) Carbohydrate (ii) Lipids and fat (iii) Proteins (iv) Vitamins (v) Minerals  (vi) Water  Elements of Nutrition : For healthy performance, each day the diet must supply the body with: A...
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INDUSTRIAL PREPARATION OF HYDROGEN  In industry, Hydrogen is manufactured from water,natural gas and ammonia..Methods are arranged in the order of their importance : (i) Electrolysis of Water : When electricity is passed through water containing a small amount of an electrolyte (an acid ,a base or salt) water decompose into hydrogen and oxygen.Hydrogen collects at cathode and oxygen gas, a by-product,is collected at anode. 2H2O ----------> 2H2 + O2 The gases produced are in the purest form.This process is expensive and is used to produce hydrogen where electricity is available at cheaper rates. (ii) Steam and Hydrocarbon Process : A mixture of steam and natural gas when over nickel catalyst at 900 C produces a mixture of hydrogen and carbon monoxide commonly known as Water gas, Natural gas contains about 94.60 % methane CH4 +H2O ---------- > 3H2 + CO (iii) By the action of steam on coal : When steam is passed over red hot coke at about 1000 C, a mixture of hydrogen and carbo...
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MANUFACTURE OF SODIUM BICARBONATE AND SODIUM CARBONATE BY SOLVAY-PROCESS : INTRODUCTION :  Solvay process was introduced by Belgian engineer Ernest Solvay (1861) for manufacture of sodium bicarbonate (baking soda) and sodium carbonate (washing soda). This process is also known as "Ammonia soda process" due to use of ammonia. DETAILS OF THE SOLVAY PROCESS : Solvay process involves the following steps: 1. AMMONIATION : Concentrated brine (sodium chloride) solution is prepared by dissolving NaCl in water.Then the brine is purified by lime-soda treatment to precipitate calcium and Magnesium as carbonate which settle down.Then the brine is pumped into a tower in which strream of ammonia gas is passed through it, the brine saturated with ammonia is called "Ammonical brine" in which CO2 is more soluble than ordinary brine. 2. CARBONATION : Carbonation involves combination of CO2 with ammonical brine. For this purpose CO2 is prepared in a skin by heating lime-stone. CaCO3 ...
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