# The minima of minimum boiling azeotropes

This is a very basic doubt, so I'll be really brief about it. The discussion I raise is particularly about minimum boiling azeotropes but it's understood that whatever I ask is about the general corresponding points. In a minimum boiling binary azeotrope phase diagram, particularly one with mole fraction on the x-axis and vapour pressure on the y axis, I understand that the composition of the azeotrope is found by taking the point of intersection of the graph representing vapour pressure as a function of the liquid composition, and the graph representing vapour pressure as a function of the vapour composition. My doubt if it is absolutely necessary within theoretical scope that that particular composition yields the minimum possible boiling point, (and hence maximum pressure) possible from either side of the phase diagram. (By which I mean vapour composition and liquid composition graphs.)

• If that's brief, I don't wanna see your verbose ;) – Mithoron Aug 6 '20 at 14:47
• What is wrong with $\mathrm{d}p(x)/\mathrm{d}x = 0$ for $x = x_{\mathrm{azeo}}$ ? – Poutnik Aug 14 '20 at 6:25
• @Poutnik I am asking if that's what the theory says. – Hardik Rajpal Aug 14 '20 at 12:06