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The conductivity of a 0.01 M solution of a 1:1 weak electrolyte at 298 K is 1.5 times 10^(-4)" S " cm^(-1). i) molar conductivity of the solution ii) degree of dissociation and the dissociation constant of the weak electrolyte Given that lambda_("cation")^(@)=248.2" S "cm^(2)mol^(-1) lambda_("anion")^(@)=51.8" S "cm^(2)mol^(-1)

Answer»

SOLUTION :Given
C = 0.01 M `""lambda_("cation")^(@)=248.2" S "cm^(2)mol^(-1)`
`K=1.5 times 10^(-4)" S " cm^(-1) " "lambda_("anion")^(@)=51.8" S "cm^(2)mol^(-1)`
(i) Molar conductivity
`wedge_(m)^(@)=(""^(@)(SM^(-1)) times 10^(-3))/(C("in M"))mol^(-1)m^(3)`
`" "^(@)=1.5 times 10^(-4)" S " cm^(-1)`
`""=(1.5 times 10^(2) times 10^(-3))/(0.01)S" "mol^(-1)m^(2)`
`1cm^(-1)=10^(2)m^(-1)`
`""=1.5 times 10^(-3)" S "m^(2)mol^(-1)`
`""=1.5 times 10^(2)`
(ii) Degree of DISSOCIATION `alpha=WEDGE^(@)/wedge_(infty)^(@)`
`wedge_(infty)^(@)=lambda_("cation")^(@)+lambda_("anion")^(@)`
`" "=(248.2+51.8)" S "cm^(2)mol^(-1)`
`" "=300" S " cm^(2)mol^(-1)`
`" "=300 times 10^(-14)" S "m^(2)mol^(-1)`
`alpha=(1.5 times 10^(-3)" S"m^(2)mol^(-1))/(300 times 10^(-4)Sm^(2)mol^(-1))`
`alpha=0.05`


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