Advertisements
Advertisements
प्रश्न
What is a cell constant? What are its units? How is it determined experimentally?
Advertisements
उत्तर
For a given cell, the ratio of separation (l) between the two electrodes divided by the area of cross-section (a) of the electrode is called the cell constant.
Cell constant = `"l"/"a"`
The unit of cell constant is m-1 (SI unit) or cm-1 (C.G.S unit).
1) The cell constant is determined using the 1 M, 0.1 M or 0.01 M KCl solutions. The conductivity of KCl solution is well tabulated at various temperatures.
2) The resistance of KCl solution is measured by Wheatstone bridge as shown in the figure.
3) AB is the uniform wire. Rx is the variable known resistance placed in one arm of Wheatstone bridge. The conductivity cell containing KCl solution of unknown resistance is placed in the other arm of Wheatstone bridge.
4) D is a current detector. F is the sliding contact that moves along AB. A.C. represents the source of alternating current.
5) The sliding contact is moved along AB until no current flows. The detector D shows no deflection. The null point is, thus, obtained at C.
6) According to Wheatstone bridge principle,
`("R"_(("solution")))/(l("AC")) = "R"_"x"/(l("BC"))`
Hence, `"R"_(("solution")) = (l("AC"))/(l("BC")) xx "R"_"x"`
7) By measuring lengths AC and BC and knowing Rx , resistance of KCl solution can be calculated.
8) The cell constant is given by
Cell constant = kKCl × `"R"_(("solution"))`
The conductivity of KCl solution is known. The cell constant, thus, can be calculated.
संबंधित प्रश्न
The molar conductivity of 0.05 M BaCl2 solution at 25° C is 223Ω-1 cm2 mol-1. What is its conductivity?
Kohlrausch law is applicable for the solution _______.
SI unit of conductivity is _______.
In case of weak electrolyte the graph Λ vs `sqrt"c"` is _______.
Give SI unit of resistivity.
Calculate molar conductivities at zero concentration for CaCl2 and NaCl.
Given: molar ionic conductivities of Ca2+, Cl–, Na+ ions are respectively, 104, 76.4, 50.1 Ω–1 cm–2 mol–1
Write relation between electrolytic conductivity and molar conductivity.
Molar conductance of BaCl2, H2SO4 and HCl at infinite dilution are X1, X2 and X3 respectively. Molar conductance of BaSO4 at infinite dilution is ____________.
What will be the concentration of NaCl solution, if the molar conductivity and conductivity of NaCl solution is 124.3 Ω−1 cm2 mol−1 and 1.243 × 10−4 Ω−1 cm2 respectively?
The molar conductance of 0.001 M acetic acid is 50 ohm−1 cm2 mol−1. The limiting molar conductance is 250 ohm−1 cm2 mol−1. What is its degree of ionization?
The molar conductances at infinite dilution `(∧_0)` for electrolytes B+A− and C+A− are 140 and 120 S cm2 mol−1. The molar conductance at infinite dilution for B+X− is 198 S cm2 mol−1. The `∧_0` (in S cm2 mol−1) of C+X− is __________.
The molar conductivities at infinite dilution for sodium acetate, HCI and NaCl are 91 S cm2 mol-1, 425.9 S cm2 mol-1 and 126.4 S cm2 mol-1 respectively. The molar conductivity of acetic acid at infinite dilution is ______.
What is the common unit of conductivity if the dimensions are expressed in centimeter?
In 2 hours, a certain current liberates 0.504 g hydrogen. How many grams of copper can be deposited by the same current flowing for the same time in a CuSO4 solution?
(Molar mass of Cu = 63.5 g mol−1, H2 = 2.0 g mol−1)
What is the relation between cell constant, conductivity and electrical resistance?
The distance between electrodes of a conductivity cell is 0.98 cm and area of cross section is 1.96 cm2. What is the cell constant?
Conductivity of a conductor is ____________.
A conductivity cell dipped in 0.01 M AgNO3 solution gives a resistance of 3160 ohms. If cell constant is 0.47 cm−1, what is the conductivity of AgNO3 solution?
What is the conductivity of 0.01 M NaCl solution if resistance and cell constant of NaCl solution are 375 ohms and 0.5 cm-1 respectively at 298 K?
Specific conductance of 0.1 M sodium chloride solution is 1.06 × 10−2 ohm−1 cm−1. Its molar conductance in ohm−1 cm2 mol−1 is ______.
What is the SI unit of conductivity?
Which of the following has least conductivity in aqueous solution?
What is the SI unit of molar conductivity?
Explain the determination of molar conductivity of a weak electrolyte at infinite dilution or zero concentration using Kohlrausch's law.
Define the term cell constant.
The resistance of a conductivity cell with cell constant 1.14 cm−1, containing 0.001 M KCl at 298 K is 1500 Ω. The molar conductivity of 0.001 MKCl solution at 298 K in S cm2 mol−1 is ______. (Integer answer)
When electric current is passed through acidified water, 112 mL of hydrogen gas at STP collected at the cathode in 965 seconds. The current passed in amperes is ______.
