One gram of `Na_(3)AsO_(4)` is boiled with excess of solid `KI` in presence of strong `HCl`. The iodine evolved is absorbed in `KI` solution and titrated against `0.2 N` hyposolution. Assuming the reaction to be
`AsO_(4)^(3-)+2H^(+)+2I^(-) rarr AsO_(3)^(2-)+H_(2)O+I_(2)`,
calculate the volume of thiosilphate hypo consumed. [Atomic weight of `As=75`]

Options

A. `48.1 mL`
B. `38.4 mL`
C. `24.7 mL`
D. `30.3 mL`

Answer

A

Explanation

molar mass `Na_(3)AsO_(4)`
`=23xx3+75+16xx4`
molar mass `=208`
eq. of `AsO_(4)^(-)=(1)/(((208)/(2)))=((1)/(104))`
equivalent of `Na_(3)AsO_(4)`= equivalent of `I_(2)`
`=` equivalent of `Na_(2)S_(2)O_(3)`
`(1)/(104)=.2xxV`
`(1)/(104xx.2)L=V=48.1 mL`