A drum contains water and 1,4-dioxane that is left over waste from an electronics cleaning facility.

For a mixture of 70 mol% water and 30 mol% 1,4-dioxane in the drum at 35

oC, calculate the following:

a) (5%) What is the mole fraction of dioxane in the vapour phase if the lid is

left of the drum and the vapour space reaches atmospheric pressure? (Hint:

you need to make some important assumptions about the vapour space).

Assume an ideal liquid solution.

b) (5%) Repeat (a) using the activity coefficient data below.

c) (5%) What is the mole fraction of oxygen in the liquid at its top surface if

the mole fraction of oxygen in the vapour space is 0.17? You need to make an

assumption based on the data you have available. Is this assumption likely to

lead to an over or under-estimate of oxygen solubility? Why have we asked

about the top surface of the liquid?

d) (5%) If the vapour space is evacuated to remove all the air and the lid

(quickly) replaced, what is the total pressure in the drum and the dioxane

mole fraction in the vapour phase? Use the activity coefficient data below.

Dioxane (A) Water (B)

Saturation Vapour pressure at 35 oC (kPa) over pure liquids 8.1 5.6

Activity coefficient with 30/70 dioxane/water (Raoultian) 3.01 1.08

Henry constant for oxygen in water, kHx (Pa) 5109