Section 4.2

4-2. Determine the mass density, ?, for the mixing process illustrated in Figure 4-2.

4-3. A liquid hydrocarbon mixture was made by adding 295 kg of benzene, 289 kg of toluene and 287 kg of p-xylene. Assume there is no change of volume upon mixing, i.e., 0??mixV, in order to determine:

1. The species density of each species in the mixture.

2. The total mass density.

3. The mass fraction of each species.

4-4. A gas mixture contains the following quantities (per cubic meter) of carbon monoxide, carbon dioxide and hydrogen: carbon monoxide, 0.5 kmol/m3, carbon dioxide, 0.5 kmol/m3, and hydrogen, 0.6 kmol/m3. Determine the species mass density and mass fraction of each of the components in the mixture.

4-5. The species mass densities of a three-component (A, B, and C) liquid mixture are: acetone, , acetic acid, , and ethanol, . Determine the ollowing for this mixture: 3326.4 kg/m??A3326.4kg/m??B3217.6 kg/m??C


1. The mass fraction of each species in the mixture.

2 The mole fraction of each species in the mixture.

3. The mass of each component required to make one cubic meter of mixture.

4-6. A mixture of gases contains one kilogram of each of the following species: methane (A), ethane (B), ropane (C), carbon dioxide (D), and nitrogen (E). Calculate the following:

1. The mole fraction of each species in the mixture

2. The average molecular mass of the mixture

4-7. Two gas streams, having the flow rates and properties indicated in Table 4.7, are mixed in a pipeline. Assume perfect mixing, i.e. no change of volume upon mixing, and determine the composition of the mixed stream in mol/m3.

Table 4.7. Composition of gas streams

Stream #1

Stream #2

Mass flow rate

0.226 kg/s

0.296 kg/s


0.48 kg/m3

0.16 kg/m3


0.90 kg/m3

0.60 kg/m3



0.220 kg/m3