page_title: Boiling
section_title: Nucleate
hierarchical_section_title: Boiling / Types / Nucleate
caption_attribution_description: English: Boling water in colour
context_page_description: Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. There are two main types of boiling: nucleate boiling where small bubbles of vapour form at discrete points, and critical heat flux boiling where the boiling surface is heated above a certain critical temperature and a film of vapor forms on the surface. Transition boiling is an intermediate, unstable form of boiling with elements of both types. The boiling point of water is 100 °C or 212 °F but is lower with the decreased atmospheric pressure found at higher altitudes.
  Boiling water is used as a method of making it potable by killing microbes and viruses that may be present. The sensitivity of different micro-organisms to heat varies. But if water is held at 100 °C for one minute, most micro-organisms and viruses are inactivated. Ten minutes at a temperature of 70 °C is also sufficient for most bacteria.
  Boiling water is also used in several cooking methods including boiling, steaming and poaching.
context_section_description: Nucleate boiling is characterized by the growth of bubbles or pops on a heated surface, which rises from discrete points on a surface, whose temperature is only slightly above the temperature of the liquid. In general, the number of nucleation sites is increased by an increasing surface temperature.
  An irregular surface of the boiling vessel (i.e., increased surface roughness) or additives to the fluid (i.e., surfactants and/or nanoparticles) facilitate nucleate boiling over a broader temperature range, while an exceptionally smooth surface, such as plastic, lends itself to superheating. Under these conditions, a heated liquid may show boiling delay and the temperature may go somewhat above the boiling point without boiling.
caption: Nucleate boiling of water over a kitchen stove burner
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