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Chemical reactions involve interaction of atoms and molecules.A large number of atoms/molecules are present in a few grams of any chemical compound varying with their atomic/molecular masses.To handle such large numbers conveniently,the mole concept was introduced.This concept has implications in diverse areas such as analytical chemistry,biochemistry,electrochemistry and radiochemistry.The following example illustrates a typical case involving chemical/electrochemical reaction.A H.O molar aqueous solution of NaCl is prepared and 500ml of this solution is electrolysed.This leads to the evolution of chlorine gas at one of the electrodes(atomic mass:Na=23,Hg=200;1 faraday=96500 coulombs).The total charge (coulombs) required for complete electrolysis is

$\begin{array}{1 1}(a)\;24125&(b)\;48250 \\(c)\;96500& (d)\;193000\end{array} $

1 Answer

$Na++e^-\rightarrow Na$
Moles of $Na^+$ discharged at cathode=2
$\therefore$ The number of electrons required for this purpose =2mole
$\therefore$ Total charge required=2 faraday.
$\Rightarrow 2\times 96500=193000$coulomb
Hence (d) is the correct answer.
answered Mar 25, 2014 by sreemathi.v

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