What will be the molar conductivity of Al 3+ ions at infinite dilution if molar conductivity of `Al^(2) (SO_(4))_(3)` is 858 S `cm^(2)` `"mol" ^(-1)` and ionic conductance of `SO_(4)^(2-)` is 160 S `cm^(2) "mol" ^(-1)` at infinite dilution ?

Explanation

According to Kohlrausch.s law ,
`Lambda^(@) [Al_2 (SO_(4))_(3)] = 2 lambda^(@) (Al^(3+)) + 3 lambda^(@) (SO_(4)^(2-))`
`Lambda^(@) [Al_(2) (SO_(4))_(3)] = 858 S cm^(2) mol^(-1)` ,
`lambda^(@) (SO_(4)^(2-)) = 160 S cm^(2) mol^(-1)`
`858 = 2 lambda^(@) (Al^(3+)) + 3 xx 160`
or `" " 2 lambda^(@) (Al^(3+) ) = 858 - 480`
`= 378`
`lambda^(@) (Al^(3+)) = (378)/(2) = 189 S cm^(2) mol^(-1)`