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Question
Assertion :Equivalent conductance increase with dilution for an electrolyte solutiion Reason: The number of ions per litre of electrolyte increases with dilution
Assertion :Equivalent conductance increase with dilution for an electrolyte solutiion Reason: The number of ions per litre of electrolyte increases with dilution
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Solution
The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Upon dilution i.e. lowering concentration, specific conductance decreases while equivalent and molar conductance increase. At infinite or almost zero concentration equivalent conductance and molar conductance attain their respective limiting values called equivalent conductance at infinite dilution ( ∧∞) or zero concentration ( ∧0) and molar conductance at infinite dilution (∧∞m) or zero concentration ( ∧∞m ), respectively. The increase of ∧ or ∧m . with the dilution of a weak electrolyte is attributable to increase of degree of dissociation with dilution resulting into more number of ions in solution. Note that ions are carriers of electricity. The increase of ∧ and ∧m . of a strong electrolyte which remains completely ionised at all dilutions, is attributed to increasing in the ionic mobilities of ions due to decrease in inter-ionic attraction. As dilution approaches infinity, the degree of dissociation of weak electrolyte approaches unity, the number of ions becomes maximum and hence ∧ as well as ∧m approach their respective maximum value. In the case of strong electrolyte, however, the maximum value of ∧ or ∧m m is attained due to the maximum ionic mobilities of the ions since at infinite dilution the dissociation of strong electrolyte is complete and inter-ionic attraction ceases to exist completely.
Upon dilution i.e. lowering concentration, specific conductance decreases while equivalent and
molar conductance increase. At infinite or almost zero concentration equivalent conductance and molar
conductance attain their respective limiting values called equivalent conductance at infinite dilution ( ∧∞)
or zero concentration ( ∧0) and molar conductance at infinite dilution (∧∞m) or zero concentration ( ∧∞m ),
respectively. The increase of ∧ or ∧m . with the dilution of a weak electrolyte is attributable to increase of
degree of dissociation with dilution resulting into more number of ions in solution. Note that ions are
carriers of electricity. The increase of ∧ and ∧m . of a strong electrolyte which remains completely
ionised at all dilutions, is attributed to increasing in the ionic mobilities of ions due to decrease in inter-ionic
attraction. As dilution approaches infinity, the degree of dissociation of weak electrolyte approaches
unity, the number of ions becomes maximum and hence ∧ as well as ∧m approach their respective
maximum value. In the case of strong electrolyte, however, the maximum value of ∧ or ∧m m is attained
due to the maximum ionic mobilities of the ions since at infinite dilution the dissociation of strong electrolyte
is complete and inter-ionic attraction ceases to exist completely.
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