Conductivities are often measured by comparing the resistance of a cell filled w
ID: 480095 • Letter: C
Question
Conductivities are often measured by comparing the resistance of a cell filled with the sample to its resistance when filled with some standard solution,such as aqueous potassium chloride. The conductivity of water is 76 mS m^(-1) at 25 C and the conductivity of 0.100 mol dm^(-3) KCl (aq) is 1.1639 S m^(-1) A cell has a resistance of 33.21ohm when filled with 0.100 mol dm^(-3) KCl (aq) and 300.0 ohm ? when filled with 0.100 mol dm^(-3) CH3COOH(aq). What is the molar conductivity of acetic acid at that concentration and temperature? ANSWER: 0.631 mS m^2 mol^(-1)
Please show the steps to arrive at this answer. Thank you!!
20.7 Conductivities are often measured by comparing the resistance of a cell filled with the sample to its resistance when filled with some standard solution, such as aqueous potassium chloride. The conductivity of water is 76 mS m at 25oC and the conductivity of0.100 mol dm 3 KCl(aq) is 1.1639 S m 1. A cell hadaresistance of 33.21 2 when filled with 0.100 mol dm 3 KCl(aq) and 300.0 2 when filled with 0.100 mol dm CHaCOOH (aq). What is the molar conductivity of acetic acid at that concentration and temperature?Explanation / Answer
SOLUTION:
Conductivity (k) = Conductance (G) X cell Constant (G*)
Conductivity (k) = 1/Resistance(R) X cell Constant (G*)
WWhen 0.1M KCL is used conductivity = 1.1639 Sm-1.
Therefore 1.1639 Sm-1 = (1 / 33.21) X G*
G* = 1.1639 X 33.21 = 38.65 m-1
When acetic acid is used
k = G G*
k = (1/R) G*
k = (1 /300) 38.65 = 0.13sm-1