Question

When N2gas is passed through water at 293k.how many moles of N2 dissolve in 1litre water

Answer 1

Answer: 7 milimoles of
`N_2` dissolve in 1 litre water.

Step-by-step explanation:

Given:
`N_2` gas is passed through water at 293K.

Assumption :
`N_2` exerts a partial pressure of 0.987 bar.

Take : Henry's constant
`p_N_2` = 76.8 Kbar

`K_H=76800`

To find : Number of moles of
`N_2` gas dissolve in 1 litre water.

According to Henry's law,

`p_N_2=K_HX_(N_2)`

`\Rightarrow\ 0.987=76800X_(N_2)`

`\Rightarrow\ X_(N_2)=(0.987)/(76800)=0.0000128515625\approx1.29*10^(-5)`

moles in 1 liter of water =
`(1000)/(18)=55.56\ [\text{Molar mass of }H_2O=18\ g]`

Let n= moles of nitrogen

Total moles = 55.56+n

So,

`X_(N_2)=(n)/(55.56+n)=1.29*10^(-5)\\\\\Rightarrow\ 55.56*1.29*10^(-5)+1.29*10^5n=n\\\\\Rightarrow\ n- 1.29*10^5n=0.000714033\\\\\Rightarrow\ 0.999987n=0.000714033\\\\\Rightarrow\ n\approx7\text{ milimoles}`

Hence, 7 milimoles of
`N_2` dissolve in 1 litre water.