The density of `3 M` sodium of thiosulphate solution `(Na_(2)S_(2)O_(3))` is `1.25 g mL^(-1)`. Calculate
a. The precentage by weight of sodium thiosulphate.
b. The mole fraction of sodium thiosulphate.
c. The molalities of `Na^(o+)` and `S_(2)O_(3)^(2-)` ions.

Options

A. `12.65%`
B. `37.92%`
C. `0.87%`
D. `63.21%`

Answer

B

Explanation

`"Molecular weight of "Na_(2)S_(2)O_(3)=158g" mol"^(-1)`
From, molarity
`=(%"by weight of solute" xx"density of solution"xx10)/(M)`
`3=(%"by weight of"Na_(2)S_(2)O_(3)xx1.25xx10)/(158)`
`:.%"by weight of "Na_(2)S_(2)O_(2)=(3xx158)/(1.25xx10)=37.92%`