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Topic : nature of oxides and hydroxides
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4
645
Engineering Entrance
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JEE Main
last time revisionThe two most important properties of oxides and hydroxides are their structure and bonding their acid-base properties. We shall consider the oxides of Group 1, Group 2, B and Al from group 3, C, Si and Pb from group 4, P, S, Cl, and the first d block. Some definitions. ionic Oxides and hydroxides are ionic if they have high melting and boiling temperatures and a crystal structure which is composed of separate ions. covalent Oxides and oxo-acids are molecular if they have low melting and boiling temperatures and they are made up of discrete molecules. A giant covalent compound has a
Topic : What is fire? A solid, liquid or gas?
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1
1478
Engineering Entrance
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JEE Main
When you light a candle, the flame has a definite shape and distinct regions are found within the flame. The first thing that happens is that the solid wax is melted, the liquid wax travels up the wick and is boiled off, becoming vaporised. The clear section at the base of the flame consists entirely of vaporised wax. Above the vaporised wax, some oxygen is present and the wax starts to react with the oxygen and burn. Wax is a hydrocarbon; in other words it is made up of hydrogen and carbon. The reactions that take place are many and complicated but there are two major processes: the oxygen reacts with the hydrogen to make water and with the carbon to produce carbon
Topic : Surface Energy and Wetting
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0
346
Engineering Entrance
,
JEE Main
For optimum adhesion, an adhesive must thoroughly “wet out” the surface to be bonded. “Wetting out” means the adhesive flows and covers a surface to maximize the contact area and the attractive forces between the adhesive and bonding surface.A lower surface energy material, such as water, will spontaneously wet out a higher energy surface, such as the un-waxed hood of a car. A waxed hood, however, has a lower surface energy than water. The water beads up rather than wet out, reducing its contact area with the surface. For a liquid adhesive to effectively wet out a surface, the surface energy of the adhesive must be as low or lower than the su
Topic : WEIRDEST BEHAVIOR OF WATER
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2
437
Engineering Entrance
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JEE Main
The most common of all liquids known to man, water, also happens to be the weirdest. The well-known strange behaviour of water, the density anomaly at 4 (degrees) C, was recorded more than three hundred years ago[1]. Since then, though that particular anomaly has been explained and understood, water has been throwing surprises, genuine and apparent, till today. To the latter category belong the episodes of "the memory effect at infinite dilutions" (the Benveniste affair) and the case of "polywater" [2]. In addition to these exotic claims, proved to be wrong subsequently, there also have been long standing genuine scientific controversies raging f
Topic : A CLASS ON CHEMICAL KINETICS
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3
640
Engineering Entrance
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JEE Main
RATES OF REACTION AND REACTION MECHANISM Chemical kinetics (kinetics): The study of the rates of chemical reactions and the steps by which they occur. Rate: Rapidity of change, a property involving time.Some chemical reactions are very fast and appear instantaneous to the eye on mixing the reactants, while others are very slow and the products only form over minutes, hours or even longer. Reaction rate: The change in concentration of a reactant or product divided by the time it takes for the change to occur. Common units are mol L−1 s−1. In this example the numerical value of the rate depends on which reactant or product concentration is being
Topic : FUEL CELLS :: LIGHTNING THE FUTURE
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0
355
Engineering Entrance
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JEE Main
Normal0falsefalsefalseMicrosoftInternetExplorer4/* Style Definitions */table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-parent:"";mso-padding-alt:0in 5.4pt 0in 5.4pt;mso-para-margin:0in;mso-para-margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:10.0pt;font-family:"Times New Roman";mso-ansi-language:#0400;mso-fareast-language:#0400;mso-bidi-language:#0400;}A fuel cell is an electrochemical device that converts the energy in chemicals into electricity. A battery is also an electrochemical device that converts chemical energy into electricity, but there is a limited supply of
Topic : THE PHYSICAL FEEL OF EMF -LECTURE 1
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5
631
Engineering Entrance
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JEE Main
v:* {behavior:url(#default#VML);}o:* {behavior:url(#default#VML);}w:* {behavior:url(#default#VML);}.shape {behavior:url(#default#VML);} Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} v:* {behavior:url(
Topic : factors affecting rate of a rxn.
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1
452
Engineering Entrance
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JEE Main
Factors that Affect the Rate of a Reaction There are 4 basic factors that can affect the rate of a chemical reaction: Temperature Concentration and pressure Physical state Catalyst 1. Temperature Temperature and rate at AS level is connected very closely with the Maxwell-Boltzmann Distribution. An increase or decre
Topic : do u know really about schrodinger equation!!!HERE IT IS
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3
583
Engineering Entrance
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JEE Main
The Hydrogen Atom Spherical polar coordinates The solution of the Schrodinger equation for the hydrogen atom is a formidable mathematical problem, but is of such fundamental importance that it will be treated in outline here. The solution is managed by separating the variables so that the wavefunction is represented by the product: The separation leads to three equations for the three spatial variables, and their solutions give rise to three quantum numbers as
Topic : Hund's Rules
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1
786
Engineering Entrance
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JEE Main
Hund's Rules 1. The term with maximum multiplicity lies lowest in energy Click on the indicated buttons for more detail. 2. For a given multiplicity, the term with the largest value of L lies lowest in in energy. 3. For atoms with less than half-filled shells, the level with the lowest value
Topic : Chemical Equivalence For Dummies!
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6
472
Engineering Entrance
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JEE Main
Chemical Equivalence for Dummies !Consider that A and B react to form a compound CA + B C1. No. of Gram Equivalents of A = No. of Gram equivalents of B 2. 3. Here n-factor could be Acidity of base, Basicity of acid, no. of electrons transfered, or valency of the species 4. i.e, Moles of A x n-factor = Moles of B x n-factor 5. Normality of A x Volume in litres = Normality of B x Volume (N1V1 = N2V2) 6. i.e, MA x n-factor x volume = MB x n-factor x volume 7. If n-factor is the
Topic : VAN DER WAALS EQUATION OF STATE
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17
1815
Engineering Entrance
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JEE Main
VAN DER WAALS EQUATION OF STATE The Ideal Gas Law, PV = nRT, can be derived by assuming that the molecules that make up the gas have negligible sizes, that their collision with themselves and the wall are perfectly elastic, and that the molecules have no interactions with each other. But this equation is applicable only for ideal gases i.e, gases at low pressure and high temperature. The van der Waal's equation is a second order approximation of the equation of state of a gas that will work even when the density of the gas is not low. The vanderwall equation is given by Here a and b are constants particular to a given gas.
Topic : Chemical Equations and Constants
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2
309
Engineering Entrance
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JEE Main
Chemical Equations and Constants Atomic Structure ^E = hvc = (wavelength)(frequency)wavelength = h / mvp = mvEn = -2.178 * 10-18 / n2 joule E = enrgyv = frequencyp = momentumv = velocityn = principle quantum numberm = massSpeed of light, c = 3.0 * 108 ms-1Planck's constant, h = 6.63 * 10-34 JsBoltzmann's constant, k = 1.38 * 10-23JK-1Avogadro's Number = 6.022 * 1023 molecules / molElectron charge, e = -1.602 * 10-19 coulomb1 electron volt per atom = 96.5 kJ / mol Equilibrium Ka = [H+][A-] / [HA]Kb =
Topic : THERMODYNAMICS REVISION
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426
Engineering Entrance
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JEE Main
Thermodynamics Revision Sheet TemperatureTF=9/5 TC + 32°TC = TK - 273.15 KThe pressure,volume and temperature in kelvin of such gases obey the equationPV=nRT ----(1)Thermal expansionΔL=αLΔTSpecific Heat Capacity=ΔQ/mΔT Gas LawsBoyles Law: PV=constantCharles Law : V/T=constantDalton Law of Partial Pressure: P=P1 + P2 +P3Root mean Square VelocityVrms=√3RT/MMean VelocityVm=√8RT/πMMost Probable VelocityV=√2RT/MAlsoVrms > Vm > VAverage kinetic Ene
Topic : CHEMISTRY PORTIONS FOR IIT
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3
722
Engineering Entrance
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JEE Main
CHEMISTRY Physical Chemistry General topics: Concept of atoms and molecules; Dalton’s atomic theory; Mole concept; Chemical formulae; Balanced chemical equations; Calculations (based on mole concept) involving common oxidation-reduction, neutralisation, and displacement reactions; Concentration in terms of mole fraction, molarity, molality and normality. Gaseous and liquid states: Absolute scale of temperature, ideal gas equation; Deviation from ideality, van der Waals equation; Kinetic theory of gases, average, root mean square and most probable velocities and their relation with temperature; Law of partial pressures; Vapour pressure; Diffusion
Topic : RATE CONSTANTS AND THE ARRHENIUS EQUATION
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3
1822
Engineering Entrance
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JEE Main
RATE CONSTANTS AND THE ARRHENIUS EQUATION This page looks at the way that rate constants vary with temperature and activation energy as shown by the Arrhenius equation. The Arrhenius equation Rate constants and rate equations You will remember that the rate equation for a reaction between two substances A and B looks like this: The rate equation shows the
Topic : Chemistry Formula ShrotCut Booklet - 1
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384
Engineering Entrance
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JEE Main
DESCRIPTION EQUATION Acid Ionization Constant Adibiatic change Base Ionization Constant Bohr Radius Boiling Point Elevation Buffer Design Equation Cell Voltage
Topic : Chemistry Formulae Must Read
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9
409
Engineering Entrance
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JEE Main
Ideal Gas law PV = nRT n = number of moles R = universal gas constant = 8.3145 J/mol K Combined Gas law P1V1 = P2V2 T1 T2 Boyle's law P1V1 = P2V2 Cha
Topic : The quantum atom
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8
3287
Engineering Entrance
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JEE Main
From orbits to orbitalsAbout ten years after Bohr had developed his theory, de Broglie showed that the electron should have wavelike properties of its own, thus making the analogy with the mechanical theory of standing waves somewhat less artificial. One serious difficulty with the Bohr model still remained, however: it was unable to explain the spectrum of any atom more complicated than hydrogen. A refinement suggested by Sommerfeld assumed that some of the orbits are elliptical instead of circular, and invoked a second quantum number, l, that indicated the degree of ellipticity. This concept proved useful, and it also began to offer some correlation with the place
Topic : chemical equilibrium
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2
468
Engineering Entrance
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JEE Main
At equilibrium ü Rate of forward reaction = Rate of backward reactionü Concentration of all entities become constantü Dynamic equilibriumü Can be attained in closed container onlyü Catalyst does not change state of equilibrium but helps in attaining it quicklyü Gibb’s free energy is minimum and entropy of universe maximumü Can be achieved from either sideü Appro
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