Advertisements
Advertisements
प्रश्न
Answer the following:
What is Kohlrausch law of independent migration of ions? How is it useful in obtaining molar conductivity at zero concentration of a weak electrolyte? Explain with an example.
उत्तर
1) Kohlrausch law states that “at infinite dilution each ion migrates independent of co-ion and contributes to total molar conductivity of an electrolyte irrespective of the nature of other ions to which it is associated.”
2) Both cation and anion contribute to molar conductivity of the electrolyte at zero concentration and thus ∧0 is the sum of molar conductivity of cation and that of the anion at zero concentration.
Thus, Λ0 `= "n"_+lambda_+^0 + "n"_(_) lambda_(-)^0`
where λ+ and λ_ are molar conductivities of cation and anion, respectively, n+ and n– are the number of moles of cation and anion specified in the chemical formula of the electrolyte.
3) Determination of molar conductivity of weak electrolyte at zero concentration:
The theory is particularly useful in calculating ∧0 values of weak electrolytes from those of strong electrolytes.
For example, ∧0 of acetic acid can be calculated by knowing those of HCl, NaCl and CH3COONa as described below:
Λ0 (HCl) + Λ0 (CH3COONa) - Λ0 (NaCl)
`= lambda_("H"^+)^0 + lambda_("Cl"^-)^0 + lambda_("CH"_3"COO"^-)^0 + lambda_("Na"^+)^0 - lambda_("Na"^+)^0 - lambda_("Cl"^-)^0`
`= lambda_("H"^+)^0 + lambda_("CH"_3"COO"_-)^0` = Λ0 (CH3COONa)
Thus, Λ0 (CH3COONa) = Λ0 (HCl) + Λ0 (CH3COONa) - Λ0 (NaCl).
Because Λ0 values of strong electrolytes, HCl, CH3COONa and NaCl, can be determined by extrapolation method, the Λ0 of acetic acid can be obtained.
APPEARS IN
संबंधित प्रश्न
The molar conductivity of 0.05 M BaCl2 solution at 25° C is 223Ω-1 cm2 mol-1. What is its conductivity?
What is a cell constant? What are its units? How is it determined experimentally?
The molar conductivity and conductivity of AgNO3 solution is 121.4 Ω–1 cm2 mol–1 and 2.428 × 10–3 Ω–1 cm–1 at 25 °C. What is molar concentration of AgNO3 solution?
Write applications of Kohlrausch’s Law.
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?
Which among the following solution has the highest conductivity (k) value?
The molar conductivities at zero concentration for Ca2+ and CaCl2 are 104 and 256.8 Ω−1 cm2 mol−1 respectively. The molar conductivity at zero concentration for Cl− 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?
Which of the following graph represents the variation of `∧` with `sqrt"c"` for acetic acid solution?
What is the cell constant of `"N"/10 "KCl"` solution at 25°C, if conductivity and resistance of a solution is 0.0112 Ω−1 cm−1 and 55.0 Ω respectively?
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 value of cell constant if conductance and conductivity of a solution is same?
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?
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?
A conductivity cell dipped in 0.5 M KCl gives a resistance of 250 ohms. If the conductivity of KC I solution is 6.68 × 10-3 S cm-1, what is the cell constant?
The value of [H3O+] in mol lit–1 of 0.001 M acetic acid solution (Ka = 1.8 × 10–5) is ______.
What is the SI unit of conductivity?
Calculate molar conductivity for 0.5 M BaCl2 if its conductivity at 298K is 0.01 Ω–1 cm–1.
Explain the determination of molar conductivity of a weak electrolyte at infinite dilution or zero concentration using Kohlrausch's law.
Define cell constant. Give its units.
