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At infinite dilution the ionic condutanc is maximum forA. `F^(-)`B. `Na^(+)`C. `H^(+)`D. `OH^(-)` |
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Answer» Correct Answer - C Since the speed of an ion varies with the potenital applied, it is better to use the term ionic mobility which is defined as the distance travelled by an ion per second under a potential gradient of `1` volt per metre. Potential gradient is given by the potential difference applied at the electrodes divided by the distance between the electrodes. The ionic mobility of `H^(+)` ions is found to be five to ten times that of other ions, expect `OH^(-)` ion. The hydrogen ion, because of its small size has high charge density and is heavily hydrated. Thus, we expect the mobility of `H^(+)` ion to be low rather than high. The high mobility of `H^(+)` ions is hydroxlytic solvents such as `H_(2)O` can be explained by Grouttus type meachanism in which a proton moves raopidly from `H_(3)O^(+)` to a hydrogen-bonded water molecule and is transferred along a series of hydrogen bonded water molecules by a rarrangement of hydrogen bonds (just like a relay race). Amongest negatives ions, `OH^(-)` has the highest ionic mobility. |
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