A closed system consists of 0.5 kmol of ammonia occupying a volume of 6 m3. Determine (a) the weight of the system, in N, and (b) the specific volume, in m3/kmol and m3/kg. Let g 5 9.81 m/s2.

Respuesta :

Explanation:

It is known that the molecular weight of ammonia ([tex]NH_{3}[/tex]) is as follows.

   Molecular weight ([tex]NH_{3}[/tex]) = [tex]14 + 3 \times 1[/tex] = 17

(a)   Therefore, we will calculate the mass as follows.

     [tex]0.5 kmol \times (\frac{1000 mol}{1 kmol}) \times (\frac{17 g}{1 mol})[/tex]

                       = 8500 g

Now, formula to calculate weight of the system in N is as follows.

            Weight = mass × g

             = [tex]8500 g \times (\frac{1 kg}{1000 g}) \times (9.8 m/s^{2})[/tex]

             = 83.3 N     (1 [tex]kg m/s^{2}[/tex] = 1 N)

Hence, the weight of the system is 83.3 N.

(b)   Relation between specific volume and number of moles is as follows.

            [tex]v (m^{3}/kmol) = \frac{V}{n}[/tex]

Therefore, calculate the specific volume as follows.

       [tex]V_m = \frac{6 m^{3}}{0.5 k mol}[/tex]

                   = 12 [tex]m^{3}/k mol[/tex]

Also,  

               [tex]v (m^{3}/kmol) = \frac{V}{m}[/tex]  

            v = [tex]\frac{6 m^{3}}{8.5 kg}[/tex]

               = 0.705882 [tex]m^{3}/kg[/tex]

Therefore, we can conclude that the value of specific volume is 12 [tex]m^{3}/k mol[/tex]  and 0.705882 [tex]m^{3}/kg[/tex].

Answer:

a) [tex]w=83.385\ N[/tex]

b) [tex]\bar V=12\ m^3.kmol^{-1}[/tex]

[tex]\b V=0.7059\ m^3.kg^{-1}[/tex]

Explanation:

Given:

no. of moles of ammonia in a closed system, [tex]n=0.5\ kmol=500\ mol[/tex]

volume of ammonia, [tex]V=6\ m^3[/tex]

We  know the molecular formula of ammonia: [tex]NH_3[/tex]

The molecular mass of ammonia:

[tex]M=14+3\times 1=18\ g.mol^{-1}[/tex]

Now the mass of given ammonia:

[tex]m=n.M[/tex]

[tex]m=500\times 17[/tex]

[tex]m=8500\ g=8.5\ kg[/tex]

a)

Now weight:

[tex]w=m.g[/tex]

[tex]w=8.5\times 9.81[/tex]

[tex]w=83.385\ N[/tex]

b)

Specific volume:

[tex]\bar V=\frac{6}{0.5}[/tex]

[tex]\bar V=12\ m^3.kmol^{-1}[/tex]

also

[tex]\b V=\frac{V}{m}[/tex]

[tex]\b V=\frac{6}{8.5}[/tex]

[tex]\b V=0.7059\ m^3.kg^{-1}[/tex]