8 7. 1 Electrolyte and electrolytic solution Out-class reading Levine, pp. 294-310 Section 10.6 solutions of electrolytes Section 10.9 ionic association pp512515 Section 16.6 electrical conductivity of electrolyte solutions
§7.1 Electrolyte and electrolytic solution Out-class reading: Levine, pp. 294-310 Section 10.6 solutions of electrolytes Section 10.9 ionic association pp. 512-515 Section 16.6 electrical conductivity of electrolyte solutions
87.1 Electrolyte and electrolytic solution 5. Conducting mechanism of electrolyte Motion of ions in the solution: 1)diffusion: due to difference in concentration Electric transfer of ion in solution 2)convection: due to the difference in density under electric field 3)transfer/migration: due to the effect of How can current cross the electrode electric field solution interface
•Electric transfer of ion in solution under electric field + + + + + + + + − + Motion of ions in the solution: 1) diffusion: due to difference in concentration 2) convection: due to the difference in density 3) transfer/migration: due to the effect of How can current cross the electrode / electric field solution interface ? I E 5. Conducting mechanism of electrolyte §7.1 Electrolyte and electrolytic solution
87.1 Electrolyte and electrolytic solution CI At anode: At cathode 2CI→Cl2+2e-↑ 2H++2e→H2个 Conducting mechanism: 1) Transfer of ion in solution under electric field 2)electrochemical reaction at electrode/solution interface
Cl− e − e − e − At cathode: 2H+ + 2e− → H2 Cl− Cl− Cl− Cl− Cl− Cl− Cl− H+ e − H+ e − H+ e − H+ H+ H+ H+ H+ H+ Cl− At anode: 2Cl− → Cl2 + 2e− H+ Cl− Conducting mechanism: 1) Transfer of ion in solution under electric field; 2) electrochemical reaction at electrode/solution interface. §7.1 Electrolyte and electrolytic solution
87.1 Electrolyte and electrolytic solution 6. Law of electrolysis For quantitative electrolysis Number 110 2sM Faraday’sLaw where m is the mass of liberated matter; Q the electric coulomb, z the number of electron gained/lost during reactions, F a proportional factor named as Faraday constant, M the molar weight of the matter Faraday 's constant FARADAY DICCTISSION F=(16021917×1019×6022169×1023)Cmol-l= Micheal Faraday 96486. C mol- usually round off as 96500 C. mol-,is Great Britain 1791-1867 the charge carried by l mole of electron Invent the electric motor and generator and the principles of electrolysis
6. Law of electrolysis where m is the mass of liberated matter; Q the electric coulomb, z the number of electron gained/lost during reactions, F a proportional factor named as Faraday constant, M the molar weight of the matter. M zF Q m = For quantitative electrolysis: Micheal Faraday Great Britain 1791-1867 Invent the electric motor and generator, and the principles of electrolysis. Faraday’s Law Faraday’s constant F = (1.6021917 10-19 6.022169 1023 ) C·mol-1 = 96486.69 C·mol-1 usually round off as 96500 C·mol-1 , is the charge carried by 1 mole of electron. §7.1 Electrolyte and electrolytic solution
87.1 Electrolyte and electrolytic solution Current efficiency (n) Application of faraday's law 1)Definition of ampere: Q theoretical 77 effective 7 IUPAC. constant current that would effective theoretical deposit 0.0011180 g of silver per second from AgNO3 solution in one second: 1 Current efficiency is lower than 100% ampere due to side-reactions. For example, 2) Coulometer: copper /silver/gas(H2, 02) evolution of hydrogen occur during coulometer electro-deposition of copper 3)Electrolytic analysis -electroanalysis O← 4)Electrochemical capacitance
Current efficiency () effective theoretical Q Q = theoretical effective m m = Current efficiency is lower than 100% due to side-reactions. For example, evolution of hydrogen occur during electro-deposition of copper. 1) Definition of ampere: IUPAC: constant current that would deposit 0.0011180 g of silver per second from AgNO3 solution in one second: 1 ampere. Application of Faraday’s law 2) Coulometer: copper / silver / gas (H2 , O2 ) coulometer 3) Electrolytic analysis – electroanalysis Q ↔m ↔ n ↔ c §7.1 Electrolyte and electrolytic solution 4) Electrochemical capacitance