Chemistry in English Hóa học bằng tiếng anh

Volume 25 Managing Editor Mahabir Singh Editor Anil Ahlawat (BE, MBA) No September 2016 Corporate Office: Plot 99, Sector 44 Institutional area, Gurgaon -122 003 (HR) Tel : 0124-6601200 e-mail : info@mtg.in website : www.mtg.in Regd Office: 406, Taj Apartment, Near Safdarjung Hospital, New Delhi - 110029 CONTENTS Class 11 NEET | JEE Essentials Examiner’s Mind 21 Ace Your Way CBSE 32 MPP-3 41 Concept Map 46 Class 12 Concept Map 47 NEET | JEE Essentials 48 Examiner’s Mind 62 Ace Your Way CBSE 69 MPP-3 75 Competition Edge Chemistry Musing Problem Set 38 78 NEET Phase II Solved Paper 2016 79 Chemistry Musing Solution Set 37 84 Crossword 85 Subscribe online at www.mtg.in Individual Subscription Rates Combined Subscription Rates yr yrs yrs yr yrs yrs Mathematics Today 330 600 775 PCM 900 1500 1900 Chemistry Today 330 600 775 PCB 900 1500 1900 Physics For You 330 600 775 PCMB 1000 1800 2300 Biology Today 330 600 775 Send D.D/M.O in favour of MTG Learning Media (P) Ltd Payments should be made directly to : MTG Learning Media (P) Ltd, Plot No 99, Sector 44, Gurgaon - 122003 (Haryana) We have not appointed any subscription agent Owned, Printed and Published by Mahabir Singh from 406, Taj Apartment, New Delhi - 29 and printed by Personal Graphics and Advertisers (P) Ltd., Okhla Industrial Area, Phase-II, New Delhi Readers are adviced to make appropriate thorough enquiries before acting upon any advertisements published in this magazine Focus/Infocus features are marketing incentives MTG does not vouch or subscribe to the claims and representations made by advertisers All disputes are subject to Delhi jurisdiction only Editor : Anil Ahlawat Copyright© MTG Learning Media (P) Ltd All rights reserved Reproduction in any form is prohibited CHEMISTRY TODAY | SEPTEMBER ‘16 STATES OF MATTER : GASES AND LIQUIDS EXISTENCE OF DIFFERENT STATES OF MATTER ª A substance may exist as solid, liquid or gas under GASEOUS STATE ª Gaseous state exists in two different forms : vapour form (exists below critical temperature) and gas form (exists above critical temperature) appropriate conditions of temperature and pressure ª A substance may also exist simultaneously in all the three states under certain specific conditions of temperature and pressure For example, water exists as ice, water and water vapour at 0.01°C and 4.58 mm of Hg pressure Such temperature of a substance is said to be its triple point ª Measurable properties of gases : z z z z Mass (S.I unit – kg) Volume (S.I unit – m3) Temperature (S.I unit – K) Pressure (S.I unit – Pa)  Mysterious new state of matter in a real material ! Researchers have just discovered the evidence of the new state known as ‘quantum spin liquid’ and it causes electrons to break down into smaller quasiparticles The electrons aren’t actually splitting down into smaller physical particles but the new state of matter is breaking electrons down into quasiparticles Quasiparticles are not actually real particles, but are concepts used by physicists to explain and calculate the strange behaviour of particles The matter itself also isn’t a liquid in the traditional sense of word, but it instead refers to the fact that the quantum spins of the electrons in the material suddenly start interacting to create a disordered state, creating all kinds of strange behaviours CHEMISTRY TODAY | SEPTEMBER ‘16 CHEMISTRY TODAY | SEPTEMBER ‘16 GAS LAWS Boyle’s Law At constant T, V ∝ or P1V1 = P2V2 P Gay-Lussac’s Law At constant V, P1 P2 = P ∝ T or T1 T2 Charles’ Law At constant P, V V t (°C) Vt = V0 + V0 or V ∝ T or = T1 T2 273.15 Gas Laws Dalton’s Law of Partial Pressures Ptotal = p1 + p2 + p3 + pn RT = (n1 + n2 + n3 + ) V Graham’s Law of Diffusion Avogadro’s Law At a given T and P, V∝n r1 d M2 = = r2 d1 M1 Graphical representations Boyles’ Law 
   
    (at const P)  
   Charles’ Law        –273.15°C °C                  
 0 = 22.4 L mol–1     ª Ideal gas equation : PV = nRT, where the constant R represents work done per degree per mole 0.0821 L atm K–1 mol–1 0.083 L bar K–1 mol–1 8.314 J K–1 mol–1 1.99 cal K–1 mol–1  
  82.05 cm3 atm K–1 mol–1 8.31 × 107 erg K–1 mol–1 8.314 dm3 kPa K–1 mol–1 5.189 × 1019 eV K–1 mol–1 KINETIC THEORY OF GASES Relation between different speeds : ump : uav : urms = : 1.128 : 1.224 ª Average kinetic energy RT K E = = kT NA per molecule MOLECULAR SPEEDS Most probable speed (ump) 2RT M 10 Average speed (uav) Root mean square speed (urms) 8RT πM CHEMISTRY TODAY | SEPTEMBER ‘16 3RT M : MAXWELL’S DISTRIBUTION OF SPEEDS   

   ª Kinetic gas equation : PV = mNu2              
 

 

   

 

  

   
  
 
   

   

   


  

 

    


   
  

 
 
  
 

   
  
       
   
  
   

 
   
   
  
  

 
  
 
     THERMODYNAMIC LAWS ª 0th Law : If the two thermodynamic systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other ª 1st Law : Total energy of the universe remains constant, although it may undergo transformation from one form to another ª 2nd Law : All spontaneous processes are thermodynamically irreversible ª 3rd Law : At absolute zero temperature, the entropy of a perfectly crystalline substance is taken as zero FIRST LAW OF THERMODYNAMICS Surroundings Surroundings System System Work Heat  =  –  Work Heat  =  +  ª State functions : Properties which are used to define a particular thermodynamic state and are independent of the path by which the state is attained are called state functions e.g., pressure, mass composition, volume, temperature, internal energy, entropy, Gibbs free energy, etc 12 CHEMISTRY TODAY | SEPTEMBER ‘16 ª Some important thermodynamic quantities : Internal energy ΔU = U2 – U1 ΔU = +ve (U2 > U1) ΔU = –ve (U2 < U1) ΔU = (cyclic process) ΔU = qv (at constant volume) M ΔU = Q × Δt × m where Q = heat capacity of the calorimeter, Δt = rise in temperature m = mass of the substance M = molecular mass of the substance Thermodynamic quantities Heat Heat evolved or absorbed, Δq = msΔt q = +ve (Heat absorbed by the system) q = –ve (Heat evolved from the system) Work Enthalpy wirr = –Pext ΔV V wrev = −2.303nRT log V1 P = −2.303nRT log P2 ΔH = ΔU + PΔV ΔH = qp (at constant pressure) In case of solids and liquids, ΔH ≈ ΔU as PΔV ≈ In case of gases, ΔH = ΔU + ΔngRT Specific heat capacity C in JK–1 g–1 Cs = m Heat capacity q C= ΔT ⎛ dq ⎞ ⎛ ∂U ⎞ Cv = ⎜ ⎟ = ⎜ ⎝ dT ⎠ v ⎝ ∂T ⎟⎠ v ⎛ ∂q ⎞ ⎛ ∂H ⎞ Cp = ⎜ ⎟ = ⎜ ⎟ ⎝ ⎝ dT ⎠ p ∂T ⎠ p Molar heat capacity C Cm = in JK–1 mol–1 n Clausius-Clapeyron Equation ΔH vap ⎛ T2 − T1 ⎞ P log = P1 2.303R ⎜⎝ T1T2 ⎟⎠ ΔHvap = Molar heat of vaporisation HESS’S LAW SECOND LAW OF THERMODYNAMICS ª Hess’s law states that, if a reaction can take place ª Entropy : Measure of degree of disorder or by more than one route and the initial and final conditions are same, the total enthalpy change is the same        ... liquid in the traditional sense of word, but it instead refers to the fact that the quantum spins of the electrons in the material suddenly start interacting to create a disordered state, creating... to make appropriate thorough enquiries before acting upon any advertisements published in this magazine Focus/Infocus features are marketing incentives MTG does not vouch or subscribe to the... | JEE Essentials 48 Examiner’s Mind 62 Ace Your Way CBSE 69 MPP-3 75 Competition Edge Chemistry Musing Problem Set 38 78 NEET Phase II Solved Paper 2016 79 Chemistry Musing Solution Set 37 84