Question

5. Henry’s Law Calculate the mass of nitrogen dissolved at room temperature (25 °C) in an 80.0-L home aquarium. Assume total pressure of 1.0 atm and a mole fraction of nitrogen of 0.78. Henry’s constant for nitrogen at 25 °C is 6.1*10-4 M/atm.

Answer 1

Ans--

From Henry's law , we know

Solubility = constant * pressure .................(1)

given, mole fraction of nitrogen is 0.78 . we know that the mole fraction is equal to partial pressur , so,pressure= 0.78 atm.

and given , constant= 6.1 *10^-4

putting these values in equation (1) we get

solubility= 6.1 *10^-4 0.78

=4.758*10^-4 M

so , we have to convert the solubility ( moles/L) into moles by multiplying with 80.0L

So, number of moles =0.0380

now , we have to convert it in mass, so Multiply 0.0380 by molar mass of N2, 28.02( g/mole) =0.0380*28.02

=1.064 g

mass of nitrogen , we will get by Multiply 1.064 g * mole fraction

mass of nitrogen = 1.064 g * 0.78

=0.83 g