Does a pure liquid in a distilling flask vaporize all at once when the boiling point is reached?
No, because the bonds are not broken at the same time within the molectule.
Why doesnt a pure liquid in a distilling flask vaporize all at once when the boiling point is reached?
The amount of heat absorbed by 1 kg of liquid to vaporize it depends on what that liquid is, (water?), and what the temperature of the liquid is at the start of the process. Obviously, it will take more heat to vaporize 1 kg of liquid that is at 0º than it will to vaporize 1 kg of liquid that is at, say, 30º.
Why doesn't a pure liquid in a distilling flask vaporise all at once when the boiling temperature is reached?
when the boiling point is reached, the molecules in the liquid will collide with each other very erratically. so molecules gain mass times velocity(momentum) and escape out of the liquid surface. but it has to have a trajectory path towards the liquid surface to get it vapourized. at boiling point, due to collisions they follow different path and may approach the walls of the distillation column or the container. so not the whole of liquid…
Liquids do not evaporate at the same rate. Every liquid has a different boiling point, and when that specific temperature is reached, the liquid will evaporate. For example, if two different liquids were in the same container, as the temperature was increasing, then the liquid with a lower boiling point would evaporate first, and the other liquid would remain a liquid until its own boiling point was reached.