Chapter 7 Electrochemistry 87.2 Conductivity and its application Out-class extensive reading Levine: pp. 506-515 16.5 electric conductivity 16.6 Electrical conductivity of electrolyte solutions
Chapter 7 Electrochemistry §7.2 Conductivity and its application Out-class extensive reading: Levine: pp. 506-515, 16.5 electric conductivity 16.6 Electrical conductivity of electrolyte solutions
87.2 Conductivity and its application Key problems How can we evaluate the ability of an electrolytic solution to conduct electricity?
Key problems: How can we evaluate the ability of an electrolytic solution to conduct electricity? §7.2 Conductivity and its application
87.2 Conductivity and its application 1. Some concepts For metals: I For electrolyte solution: Ohm’sLaw U R: resistance. electric conductance(G): R Definition: G= I/R I Unit: Ohm, Q2 Unit: Q-I. mho. Siemens. S o: resistivity Reciprocal of resistance R A Unit: Q2-m conductivity(x: nition:K=l/p Unit: m
1. Some concepts For metals: I U R = R: resistance, Unit: Ohm, A l R = : resistivity Unit: ·m Ohm’s Law For electrolyte solution: Reciprocal of resistance electric conductance (G) : Definition: G = 1/R Unit: -1 , mho, Siemens, S conductivity () : Definition: = 1/ Unit: S·m-1 §7.2 Conductivity and its application
87.2 Conductivity and its application 2. Measurement of conductance: Conductance cell and conductance electrode R R R conductance cell Wheatstone Bridge Circuit A G=K conductance electrode
l A G = ~ G A C B D R2 R1 R4 R3 I Wheatstone Bridge Circuit §7.2 Conductivity and its application conductance cell Conductance cell and conductance electrode conductance electrode 2. Measurement of conductance:
87.2 Conductivity and its application 2. Measurement of conductance: a capacitor High-frequency alternative current, ca. D 1000 Hertz R R R 4 R 电导环 RR R3×R2=R4RF4 □ca G=K R Conductometer
R3 R2 = R4 R1 4 2 3 1 R R R R = 1 1 R G = 2. Measurement of conductance: ~ G A C B D F R2 R1 R4 R3 I R2 l A G = High-frequency alternative current, ca. 1000 Hertz ? Conductometer a capacitor! §7.2 Conductivity and its application