The volume of nitrogen gas Um (measured at STP) required to cover a sample of silica get with a mono-molecular layer is `129 cm^(3) g^(-1)` of gel. Calculate the surface area per gram of the gel if each nitrogen molecule occupies `16.2 xx 10^(-20) m^(2).`

Answer

`561.8 CM^(3)`

Explanation

`22400 cm^(3)` of `N_(2)` at STP contain `=6.022xx10^(23)` molecules
`:. 129 cm^(3)` of `N_(2)` at STP will contain `=(6.022xx10^(23)xx129)/(22400)=3.468xx10^(21)` molecules
Area occupied by a single molecule `=16.2xx10^(-20) m^(2)`
Area occupied by `3.468xx10^(21)` molecules of nitrogen `=(16.2xx10^(-20))xx(3.468xx10^(21)) m^(2)=561.8 m^(2)`