One litre solution of `MgCl_(2)` is electrolyzed completely by passing a current of 1A for 16 min 5 sec.The ogiginal concentration of `MgCl_(2)` solution was(Atomic mass of Mg=24)

Options

A. `5 xx 10^(-3)` M
B. `5 xx 10^(-2)` M
C. `0.5 xx 10^(-3)` M
D. `1.0 xx 10^(-2)` M

Answer

A

Explanation

(a) : Current = 1 A, time = 16 min 5 sec = 965 sec Quantity of electricity passed = current `xx` time
= 1 `xx` 965
= 965 C
w = ZIt (where w= amount of substance deposited)
`w = (12)/(96500) xx 965 ( :' Z = (E)/(96500)) = (12)/(100)`
Conc. of `MgCl_(2) = ("Weight")/("Mol.mass" xx V(L)) = (12)/(100xx24xx1)`
`= 1/(200) = 5 xx 10^(-3)` M