Calculate the mass of nitrogen dissolved at room temperature in an 99.0 L home aquarium. Assume a total pressure of 1.0 atm and a mole fraction for nitrogen of 0.78. Express your answer using two significant figures.

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Answer:

88.48 grams of Nitrogen

Explanation:

To calculate this, you have to use the ideal gas equation

P x V = n x R x T

Where P = pressure (1 atm)

V = Volume (99 L)

n = moles

R = ideal gas constant (0.082 atm x L /(K x mol))

T = Temperature in Kelvin (25 Celsius = 298 K)

(1 atm x 99 L)/0.082atm x L /(K x mol)x298 K = n

4.05 moles = n

This is the total amount of moles in the aquarium, but you are only interested in Nitrogen, and the mole fraction for nitrogen is 0.78, so you have:

4.05 moles x 0.78 = 3.16 moles of Nitrogen

One mol of Nitrogen (N2) has a mass of 28 grams, so in 3.16 moles you have:

3.16 x 28 grams = 88.5 grams of Nitrogen

Explanation:

The given data is as follows.

         [tex]P_{total}[/tex] = 1 atm,        [tex]X_{NO_{2}}[/tex] = 0.78

Now, we will calculate the partial pressure of given nitrogen gas as follows.

             [tex]P_{NO_{2}} = X_{2}P_{total}[/tex]

                        = [tex]0.78 \times 0.78[/tex]

                        = 0.78 atm

According to the Henry's law we will calculate the solubility of nitrogen as follow.

              [tex]S_{N_{2}} = K_{H}P_{N_{2}}[/tex]

                       = [tex]6.1 \times 10^{-4} M/atm \times 0.78 atm[/tex]

                       = [tex]4.758 \times 10^{-4} M[/tex]

Now, for 99.0 L the amount of nitrogen gas dissolved is calculated as follows.

[tex]\frac{99.0 L N_{2} \times 4.758 \times 10^{-4} M \times 28.0134 g N_{2}}{1 L N_{2} \times 1 mol N_{2}}[/tex]

        = [tex]13195.49 \times 10^{-4}[/tex]

        = 1.32 g

Thus, we can conclude that the mass of nitrogen dissolved at room temperature in an 99.0 L home aquarium is 1.32 g.