Boiling (source code)
= Boiling
{wiki}
Boiling is <vaporization> through the formation and growth of vapor bubbles within a <liquid>. It differs from surface <evaporation>, which can occur without bubbles in the bulk. At equilibrium, the <boiling point> of a pure liquid is set by equality of its saturation <vapor pressure> and the external <pressure>.
A real bubble must also overcome local hydrostatic pressure and the <capillary pressure> of its curved surface. Creating the interface costs <energy>, giving a <nucleation barrier>; a smooth clean vessel can therefore permit <superheating>. Surface cavities and <boiling chips> supply sites where bubbles form more readily. The observed onset depends on these sites and heating conditions, while the equilibrium boiling point remains a property specified at the chosen pressure.
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