In `N_(2)` gas is bubble through water at 293 K, how many millimoles of `N_(2)` gas would dissolve in 1 litre of water? Assume that `N_(2)` exerts a partial pressure of 0.987 bar. Given that henry's law constant for `N_(2)` at 293 K is 76.48 k bar.

Answer

0.717 mmol

Explanation

According to Henry.s law, `p_(N_(2))=K_(H).x_(N_(2))`
or `x_(N_(2))=(p_(N_(2)))/(K_(H))=(0.987"bar")/(76.48xx10^(3)"bar")=1.29xx10^(-4)`
Mass of 1 litre water = 1000g
No. of moles of water in 1 litre `=(1000)/(18)=55.5`
If n is the number of `N_(2)` in solution, `x_(N2)`
`=(n)/(n+55.5)=(n)/(55.6)=1.29xx10^(-4)`
or n `55.6xx1.29xx10^(-4)"mol"=71.7xx10^(-4)"mol"=0.717` m mol.