Can the evaporation process occur at a lower temperature?
It is possible to make the evaporation process happen at an even lower temperature – by reducing the chance of the escaping molecules bouncing back into the liquid. To do this we need to make the molecules in the air above the liquid spread out even further, in other words reduce the air pressure. This is the reason why water boils at a lower temperature up a high mountain where air pressure is lower than at sea level. But we don’t have to climb Mount Everest to reduce the air pressure. Instead, we can use a siphon pump. A siphon pump increases the space a fixed mass of air has to fill, thereby reducing its pressure. What liquids could we use as a coolant? There are a number of possibilities but it depends on two key properties: boiling point and latent heat of vaporisation. The latent heat of vapourisation of a liquid is the amount of energy in joules required to turn one gram of the liquid into a vapour. When you get out of the shower or bath and feel cold it is because for every gra
