Question

Question 1.

a) Draw a vapour pressure (pA) vs composition (xA) graph for an ideal solution of A mixed with B.

b) Sketch a curve that you might see for a real solution where A interacts more strongly with itself than it does with B.

c) Label the region of this graph that follows Henry’s Law.
d) Will the Henry’s Law constant for A be larger or smaller than vapour pressure of pure A? Explain your answer in one sentence.

e) Label the region of the graph where the solution behaves like a ideal real solution.
f) Will the boiling point of the real solution be greater than or less than the boiling point of the corresponding ideal solution? Explain your reasoning in one sentence.

g) Will the activity of A in this solution be greater than or less than xA? Use the appropriate equation(s) to explain your answer.

Answer 1

A) , B) &C)
D)   Henry's law constant will be lesser than the vapor pressure of pure A
K_H = C / P_a ; P_a = X_aP_a^*
   K_H = C /  X_aP_a^*
f) An ideal solution obeys Raoult's law , lower the vapor pressure higher the boiling point but real solutions
lower vapor pressures than ideal solutions therefore the boiling point of real solutions are less than ideal ones
g) Activity coeffcient , γ = P_TY_A / P_AX_A
From the above equationit is clear that activity coeffcient > X_A