Kohlrausch's Law and its Application

IMPORTANT

Kohlrausch's Law and its Application: Overview

This topic covers concepts such as Kohlrausch's Law, Applications of Kohlrausch's Law, Determination of Molar Conductivity of a Weak Electrolyte at Given Concentration, Determination of Solubility of a Sparingly Soluble Salt, etc.

Important Questions on Kohlrausch's Law and its Application

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IMPORTANT

The law that states about independent migration of ions is:

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IMPORTANT

Electrolyte KCl KNO3 HCl NaOAc NaCl
 S cm2 mol-1 149.9 145.0 426.2 91.0 126.5


Calculate  Λ o HOAC  at infinite dilution in   H 2 O at   25°C :

MEDIUM
IMPORTANT

The molar conductance at infinite dilution for sodium acetate, hydrochloric acid and sodium chloride are 91.0, 426.2 and 126.5 S cm2mol-1 respectively at 298 K. The molar conductance of acetic acid at infinite dilution would be

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The molar conductance and the specific conductance of an electrolyte are related by the formula

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The molar conductance of 0.01 M electrolyte is 124 ohm-1 cm2 mol-1 at 298 K. Calculate its specific conductance.

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The specific conductance of 0.01 M of an electrolyte is 1.24×10-3 ohm-1 cm-1 at 298 K. Calculate the molar conductance.

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Calculate the molar conductance of 0.02 M solution of an electrolyte which has a resistance of 310 ohm at 298 K. Cell constant is 0.68 cm-1.

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0.05 M NaOH offered a resistance of 31.2 ohm in a conductivity cell having a cell constant of 0.38 cm-1. Calculate the molar conductivity of NaOH solution.

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Calculate the molar conductance of 0.01 M solution of an electrolyte which has a resistance of 210 ohm at 298 K. Cell constant is 0.88 cm-1.

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Specific conductance of 0.1 M CH3COOH is 4.7×10-2 ohm-1 cm-1 at 298 K. Calculate its molar conductance.

MEDIUM
IMPORTANT

Which statement is not correct for Kohlrausch law?

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If the value of molar conductivities at infinite dilution for CH3COOHHCl and NaCl are 390.5, 425.4 and 126.4 S cm2mol-1 respectively at 298 K. Calculate the molar conductivity at infinite dilution of CH3COONa in S cm2mol-1. (Just mention the value, no requirement of units in the answer).

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The molar conductivity of a solution of a weak acid HX (0.01 M) is 10 times smaller than the molar conductivity of a solution of a weak acid HY (0.10 M). If λ°X-=λ°Y-, the difference in their pKa values, pKa(HX)-pKa(HY), is (consider degree of ionization of both acids to be <<1)

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Λ°m for NaCl, HCl and NaAc are 126.4, 425.9 and 91.0 S cm2 mol-1 respectively. Calculate Λ°m for HAc.

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The maximum molar conductivities of X+3 and Y- ions are 200 and 100 S cm2 mol-1 respectively. The molar conductivity of XY3 at infinite dilution is :-

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What is meant by limiting molar conductance ?

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The molar conductivity of 0.025 mol L-1 methanoic acid is 46.1 S cm2 mol-1. Calculate the degree of dissociation. Given : λ°(H+)=349.6 S cm2 mol-1λ°(HCOO-)=54.6 S cm2 mol-1.

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The molar conductivities at infinite dilution for CH3COONa, HCl and NaCl are 91.0, 425.9 and 126.4 S cm2 mol-1 respectively at 298K. Calculate the molar conductivities of CH3COOH at infinite dilution.

MEDIUM
IMPORTANT

State Kohlrausch law of independent migration of ions. Why does the conductivity of a solution decrease with dilution?

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Consider the galvanic cell, Pt(s)H2(1 bar)HCl(aq)(1 M)Cl(1 bar)Pt(s). After running the cell for sometime, the concentration of the electrolyte is automatically raised to 3 M HCl. Molar conductivity of the 3 M HCl is about 240 S cm2 mol-1 and limiting molar conductivity of HCl is about 420 S cm2mol-1. If Kb of water is 0.52 K kg mol-1, calculate the boiling point of the electrolyte at the end of the experiment.