Chemical reactions involve interaction of atoms and molecules. A large number of atoms and molecules (approximately `6.022 xx 10^(23)`) are present in a few grams of any chemical compound varying with their atomic/molecular masses. To handle such a large number conveniently, the mole concept was introduced. This concept has implications in diverse areas such as analytical chemistry, biochemistry, electrochemistry and radiochemistry. The following example illustrate a typical case involving chemical/electrochemical reaction which requires a clear understanding of mole concept.
A 4.0 molar aqueous solution of NaCl is prepared and 500 mL of the solution is electrolyzed. This lead to the evolution of chlorine gas at one of the electrodes (atomic mass : Na = 23 , Hg = 200 , 1F = 96500 C)
The total number of moles of chlorine gas evolved is :

Options

A. `0.5`
B. `1.0`
C. `2.0`
D. `3.0`

Answer

B

Explanation

`NaCI rarr Na^(+) +CI^(-)`
At anode `2CI^(-) rarr CI_(2)`
moles of `CI^(-) =2` in `500ml`
i.e 1 mole of `CI_(2)` evolved