Evaporation – the natural physical process caused by continuous motion of the molecules in liquid. It is important to note that evaporation of water happens at any ambient temperature.
If to leave the container with water open, then through a certain period all liquid from it will evaporate. Evaporation – physical process of transition of substance of liquid state in gaseous. In water, as well as in any other liquid, there are molecules which kinetic energy allows them to overcome an intermolecular attraction. These molecules with a force disperse and take off on a surface. Therefore if to cover glass with water with a tissue, then after a while it will become a little damp. But evaporation of water in different conditions proceeds with various intensity. The key physical characteristics influencing the speed of course of this process and its duration are the substance density, temperature, surface area, wind existence. The more substance density, the molecules are located more closely to each other. So, it is more difficult to them to overcome an intermolecular attraction, and they in much smaller quantity take off on a surface. If to place two liquids with a different density (for example, water and methyl alcohol) in identical conditions, then that which density is less will quicker evaporate. Density of water is equal to 0.99 g/cm3, and density of methyl alcohol - 0.79 g/cm3. Therefore, methanol will evaporate quicker. Not less important factor influencing water evaporation speed is temperature. As it was already told, evaporation happens at any temperature, but with its increase the speed of motion of the molecules grows, and they in bigger quantity I begin to leave liquid. Therefore the burning water evaporates quicker, than cold. The intensity of evaporation of water depends as well on the area of its surface. The water poured in a bottle with a narrow neck will slowly evaporate since the taken-off molecules will settle on the walls of a bottle which are narrowed above and to roll down back. And molecules of the water which is in a saucer will freely leave liquid. Evaporation process considerably will accelerate if over a surface to which there is an evaporation air flows move. The fact is that besides an exit of molecules from liquid there is their return back. And the air circulation is stronger, the it is less than molecules, falling, will get back to water. So, its volume will promptly decrease.