Question

Pure hexane (C6) exists as V + L as shown. Pure heptane (C7) liquid is injected into the vapor at constant temperature and pressure. After injection the overall mixture is 10 mol% C7. What happens (circle the best answer)?

(a) All the C7 goes to L and the V is only C6.

(b) The vapor is mostly C6 with some C7.

(c) All the vapor condenses.

(d) All the liquid evaporates.

(e) None of the above. Explain

Answer 1

c)all vapour condenses

this can be best understood with Txy or Pxy diagram for

hexane & heptane

as we know hexane is more volatile than heptane

in this diagram light key component will be hexane

initially pure hexane is there

here we can see that extrem right end is pure hexane & after adding 10% heptane

we maintain same T & P

so we draw straight line to reach that point where hexane is 0.9 & we came to know its liquid phase ....

so

all vapour condeses is best answer