Do azeotropes evaporate, without boiling, in proportionate amounts, or does this property describe their behaviour only at boiling point?
Concretely, if 91% isopropyl alcohol/water (by volume, i.e. an azeotropic mixture) is left open at say 25 °C, will it remain in that proportion as it evaporates, or become more dilute (until just water) as the alcohol evaporates faster?
Further, above this point, would the alcohol evaporate faster 'degrading' it until 91% at which point it behaves as the answer to above? (Which would incline me to think the answer is no, if not boiling the water and alcohol would evaporate 'independently' and the alcohol concentration would fall no matter the starting point, it's not magic.)