Tiêu đề 4_Ionic Equilibrium.docx ✅

PRE-MEDICAL 69 PHYSICAL CHEMISTRY Serial No. MODULE-1 Page No. 1. Some basic concepts of Chemistry 2. Atomic structure 3. Chemical Equilibrium 4. Ionic Equilibrium 5. Thermodynamics & Chemical Energetics 6. Redox reactions 7. Behaviour of Gases 8. Hints and Solutions
PRE-MEDICAL 69 IONIC EQUILIBRIUM S.No. CONTENTS Page No. 1. Introduction 2. Ostwald’s dilution law 3. Explanation of water 4. Salts, types of salts and conjugate theory 5. Hydrolysis of salts 6. Solubility and solubility product 7. Few important points 8. pH 9. Buffer solution 10. Indicators 11. Acid and Base 12. Exercise-I (Conceptual Questions) 13. Exercise-II (Previous Years Questions) 14. Exercise-III (Analytical Questions) 15. Exercise-IV (Assertion & Reason)
PRE-MEDICAL 69 IONIC EQUILIBRIUM 4.0 INTRODUCTION Formulae : (i) In x = log e x = 2.303 log 10 x = 2.303 logx (ii) log (x×y) = log x + log y (iii) log x y    = logx – logy (iv) logx y = ylog x Ex. (i) log 6 = log (2×3) = log2 + log3 = 0.3010 + 0.47711 = 0.7781 (ii) log 30 = log (3×10) = log3 + log10 = log 0.4771 + 1 = 1.4771 (iii) log 1000 = log 10 3 = 3log 10 = 3×1 = 3 A. Some values of log : log1 = 0 log2 = 0.3010 log3 = 0.4771 log4 = 0.6020 log5 = 0.699 log6 = 0.7781 log7 = 0.8451 log8 = 0.9030 log9 = 0.9542 log10 = 1 log11 = 1.04 log100 = 2 log1000 = 3 Some terms which are used in ionic equilibrium : Antilog : Antilog (x) = 10 x Ex. Antilog (2) = 10 2 = 100 Antilog (0.3010) = 10 .3010 2 Antilog [log(2)] = Antilog (0.3010) = 2 pH – Scale : Given by – Sorenson pH Scale is called Sorenson scale. pH scale is a measuring scale used to measure strength of acid and base and its value is equal to –log[H + ] i.e. pH = –log[H + ] = log 1 [H] Ex. [H + ] = 10 –3 pH = –log 10 –3 = + 3 log 10 = 3 Conclusion :
PRE-MEDICAL 69 If pH = x then [H + ] = 10 –x or Vice versa i.e. If [H + ] = 10 –x then pH = x pOH  It is equal to –log [OH – ] i.e. pOH = –log [OH – ] = log 1 [OH] Ex. If X = a b ×10 –c , then find pX? Sol. pX = –logX = –log ca 10 b     pX = – ca loglog10 b     = –[loga – logb – c] pX = c + logb – loga pH scale at 25°C Figure According to conductivity substances are of two types : (1) Non-Conductor – Those substance which do not show the flow of current or electricity. Ex. Non-metals, plastic, plastic, rubber, wood etc. Exception – Graphite is a non-metal but show conductivity due to motion of free electrons. (2) Conductors – Those substance which show conductivity or flow of current are called conductors and these are of two types : (a) Metallic conductor –Those conductor which show conductivity due to motion of free electrons. (b) Ionic conductors – Those conductor which show conductivity due to movement of free ions. Ions are in free state in the solutions of ionic compounds. On passing electric current through the solution, ions move towards oppositely charged electrodes, i.e., the cation moves towards cathode (negative electrode) and the anion moves towards anode (positive electrode). Due to this reason, they are called cations and anions respectively. The current flows through the solution due to the movement of the ion Movement of ions through the solution of electrolyte (AgNO 3 ) towards oppositely charged electrodes. Figure According to strength, ionic conductors are of two types- (1) Strong electrolytes – Those ionic conductors which are completely ionized in aqueous solution are called as strong electrolytes. For strong electrolyte the value of degree of ionization is 100% i.e.  = 1 Ex. (a) Strong acid  H 2 SO 4 , HCl, HNO 3 , HClO 4 , HBr, HI (b) Strong base  KOH, NaOH, Ba(OH) 2 , CsOH, RbOH (c) All salts  NaCl, KCl, CuSO 4 ………