Question

Liquid pentane is stored in a large vessel that has access to the atmosphere. The local temperature (T) is 25 °C The local atmospheric pressure is 760 mm Hg.

The Antoine constants for pentane and water are shown in Table 1.

The Antoine equation is log10(p°, in mm Hg) = A - (B/(T + C)) where T is in °C.

a- Estimate the partial pressure of air and the composition (in mol fractions) of all components in the air/vapour mixture in the space above the liquid.

b- Estimate the composition (with respect to pentane) of head gas corresponding with a stoichiometric mixture of pentane and oxygen (in air) and state which component is in excess and by how much, in relation to complete combustion of pentane, in the space above the liquid in the vessel

c- After a storm, rain water enters the vessel and forms an immiscible mixture with the pentane. Estimate the temperature at which all the air will be driven from the space above the liquid in the vessel.

Table 1. Antoine constants for pentane and water (up to 60 °C)

Pentane A: 6.884471 / B: 1060.793 / C: 231.541

Water A: 8.10765 / B: 1750.286 / C: 235.0

Answer 1

Here you can observe the water in liquid phase where Pentland and oxygen and nitrogen all exist in gas phase at 33.425 ⁰C

hence they will be seperated