Physical chemistry Electrochemistry (3 Xuan Cheng Xiamen University
1 Electrochemistry(3) Xuan Cheng Xiamen University Physical Chemistry
Ch ical chemistr ectrochemid四 Electrolytic Conductivity The electric current l (1646) The electric current densit (1647) The conductivity K K≡ y j=KE (1649) E The reciprocal of conductivity (resistivity)p (1650)* K
2 Physical Chemistry Electrolytic Conductivity Electrochemistry The electric current I (16.46)* dt dQ I (16.47)* A I j The electric current density j The conductivity The reciprocal of conductivity (resistivity) (16.50)* 1 (16.49)* E j j = E
Ch ical chemistr ectrochemid四 Electrolytic Conductivity The resistance R Rs/4/ (1646)* R ohm (1654) The conductance G A 电导G=x4长度= G=K 面积=A 1s=1g1 单位立方体 Siemens mho 电导率x 电导率的定义
3 Physical Chemistry Electrolytic Conductivity l A G = The resistance R (16.46)* I R | | A l R = (16.54) The conductance G 1 S=1 -1 Siemens ohm -1 mho Electrochemistry
Ch ical chemistr ectrochemid四 Molar Conductivity The conductivity of a solution -k I mol depends on the number of ions present The molar conductivity Am 单位间距 单位立方体 K 单位面积 电导率x (1658) (b) C 摩尔电导率的定义 The electrolyte s stoichiometric molar concentration
4 Physical Chemistry Molar Conductivity The conductivity of a solution depends on the number of ions present The molar conductivity m c m Electrochemistry (16.58)* c m The electrolyte’s stoichiometric molar concentration
choical Chemistry Elcctrochemiary Molar Conductivity K KVs。C (1658)* HoSO Strong electrolytes H2SO4 KOH Fully ionized in solution: ionic KCI KOH solids, strong acids and bases The concentration of ions is proportional to the concentration of electrolyte added OA CHCOOI 0 10 Weak electrolytes MgSO CH, COOH c/(mol-dm Neutral electrolytes KCl Conductivity Vs. concentration
5 Physical Chemistry H2SO4 KOH KCl MgSO4 CH3COOH 0 5 15 10 c/(moldm-3 ) 20 40 60 80 Conductivity vs. concentration k/( Sm-1 ) 0 vs. c Strong electrolytes Fully ionized in solution: ionic solids, strong acids and bases The concentration of ions is proportional to the concentration of electrolyte added Weak electrolytes MgSO4 CH3COOH Neutral electrolytes KCl H2SO4 KOH Molar Conductivity Electrochemistry (16.58)* c m
Chical chemistr Elcctrochemiary Molar conductivity In an extensive series of measurements during 19th century, Friedrich Kohlrausch The limiting molar conductivity At low concentrations 400 A=A-K 300 The infinite-dilute molar conductivity A++A=vn+vn 200 100 AgNO The infinite-dilute molar conductivity of the cations and anions CHCOOH Law of the independent migration of ions 0.5 1.5
7 400 300 200 100 3 B/mol dm− c m/(Scm 2 mol -1 ) HCl NaOH AgNO3 CH3COOH 0 0.5 1.0 1.5 In an extensive series of measurements during 19th century, Friedrich Kohlrausch At low concentrations + + − − = + + − = + m m m The infinite-dilute molar conductivity K c m = m − The infinite-dilute molar conductivity of the cations and anions Law of the independent migration of ions Molar Conductivity Physical Chemistry o m The limiting molar conductivity Electrochemistry