428:, requiring exceeding the boiling point by several degrees Celsius. Once a bubble does begin to grow, the surface tension pressure decreases, so it expands explosively in a positive feedback loop. In practice, most containers have scratches or other imperfections which trap pockets of air that provide starting bubbles, and impure water containing small particles can also trap air pockets. Only a smooth container of purified liquid can reliably superheat.
741:
107:
132:
Surface tension makes the bubble act like an elastic balloon. The pressure inside is raised slightly by the "skin" attempting to contract. For the bubble to expand, the temperature must be raised slightly above the boiling point to generate enough vapor pressure to overcome both surface tension and
469:
from the solvent. There are ways to prevent superheating in a microwave oven, such as putting a non-metallic object (such as a stir stick) into the container beforehand or using a scratched container. To avoid a dangerous sudden boiling, it is recommended not to microwave water for an excessive
460:
points. Superheating is more likely after repeated heating and cooling cycles of an undisturbed container, as when a forgotten coffee cup is re-heated without being removed from a microwave oven. This is due to heating cycles releasing dissolved gases such as
136:
What makes superheating so explosive is that a larger bubble is easier to inflate than a small one; just as when blowing up a balloon, the hardest part is getting started. It turns out the excess pressure
641:"A series of superheated water with oil film experiments done in the microwave by Louis A. Bloomfield, physics professor at the University of Virginia. Experiment #13 proceeds with surprising violence"
125:
Superheating is an exception to this simple rule; a liquid is sometimes observed not to boil even though its vapor pressure does exceed the ambient pressure. The cause is an additional force, the
361:
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400:
217:
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114:
Water is said to "boil" when bubbles of water vapor grow without bound, bursting at the surface. For a vapor bubble to expand, the temperature must be high enough that the
426:
158:
452:, potentially spraying boiling water out of the container. The boiling can be triggered by jostling the cup, inserting a stirring device, or adding a substance like
178:
19:
This article is about the phenomenon where a liquid can exist in a metastable state above its boiling point. For pressurized water above 100 °C, see
678:
405:
This means if the largest bubbles in a container are small, only a few micrometres in diameter, overcoming the surface tension may require a large
456:
or sugar. The chance of superheating is greater with smooth containers, because scratches or chips can house small pockets of air, which serve as
222:
This can be derived by imagining a plane cutting a bubble into two halves. Each half is pulled towards the middle with a surface tension force
606:
110:
For boiling to occur, the vapor pressure must exceed the ambient pressure plus a small amount of pressure induced by surface tension
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507:
28:
1015:
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1137:
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79:, where boiling might occur at any time, induced by external or internal effects. Superheating is achieved by heating a
542:
Debenedetti, P.G.Metastable
Liquids: Concepts and Principles; Princeton University Press: Princeton, NJ, USA, 1996.
254:
1183:
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1162:
1061:
691:
94:
water in a very smooth container. Disturbing the water may cause an unsafe eruption of hot water and result in
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Video of superheated water in a microwave explosively flash boiling, why it happens, and why it's dangerous.
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prevents boiling, leaving the surface calm. However, once the water is disturbed, some of it violently
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68:
59:
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512:
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122:, primarily). Below that temperature, a water vapor bubble will shrink and vanish.
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740:
91:
55:
24:
1005:
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Superheating can occur when an undisturbed container of water is heated in a
492:
75:
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106:
1142:
970:
570:"Risk of Burns from Eruptions of Hot Water Overheated in Microwave Ovens"
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16:
Heating a liquid to a temperature above its boiling point without boiling
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Vapor-compression refrigeration § Thermodynamic analysis of the system
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27:. For the 'superheat' used in vapor-compression refrigeration, see
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105:
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due to surface tension is inversely proportional to the diameter
95:
660:
716:
619:
Urban
Legends Reference Pages: Superheated Microwaved Water
251:, which must be balanced by the force from excess pressure
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Health, Center for
Devices and Radiological (2018-11-03).
587:
Critical
Droplets and Nucleation, Cornell Solid State Lab
597:
411:
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310:
257:
228:
186:
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143:
553:"Negative Pressures and Cavitation in Liquid Helium"
440:. At the time the container is removed, the lack of
1090:
1044:
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830:
804:
748:
699:
420:
394:
356:{\displaystyle \Delta p(\pi d^{2}/4)\propto \pi d}
355:
296:
243:
211:
172:
152:
87:, while taking care not to disturb the liquid.
601:Published by Oxford University Press US, 1994
672:
8:
297:{\displaystyle \Delta p\times (\pi d^{2}/4)}
23:. For the device used in steam engines, see
478:Superheating of hydrogen liquid is used in
679:
665:
657:
129:, which suppresses the growth of bubbles.
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333:
327:
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283:
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83:substance in a clean container, free of
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395:{\displaystyle \Delta p\propto d^{-1}}
212:{\displaystyle \Delta p\propto d^{-1}}
7:
652:Video of superheated water in a pot.
563:
561:
412:
370:
311:
258:
187:
144:
118:exceeds the ambient pressure (the
14:
739:
508:Critical point (thermodynamics)
50:) is the phenomenon in which a
551:Maris, H., Balibar, S. (2000)
341:
317:
291:
267:
244:{\displaystyle F\propto \pi d}
1:
1128:Macroscopic quantum phenomena
432:Occurrence via microwave oven
1138:Order and disorder (physics)
1210:
42:(sometimes referred to as
18:
737:
1163:Thermo-dielectric effect
1062:Enthalpy of vaporization
756:Bose–Einstein condensate
421:{\displaystyle \Delta p}
180:of the bubble. That is,
153:{\displaystyle \Delta p}
1189:Thermodynamic processes
1057:Enthalpy of sublimation
1072:Latent internal energy
822:Color-glass condensate
422:
396:
363:, which simplifies to
357:
298:
245:
213:
174:
154:
111:
66:. This is a so-called
882:Magnetically ordered
639:Bloomfield, Louis A.
423:
397:
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175:
155:
109:
761:Fermionic condensate
555:Physics Today 53, 29
409:
367:
308:
255:
226:
184:
164:
141:
120:atmospheric pressure
976:Chemical ionization
868:Programmable matter
858:Quantum spin liquid
726:Supercritical fluid
503:Bumping (chemistry)
44:boiling retardation
1123:Leidenfrost effect
1052:Enthalpy of fusion
817:Quark–gluon plasma
418:
392:
353:
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241:
209:
170:
150:
133:ambient pressure.
112:
90:This may occur by
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1153:Superheated vapor
1148:Superconductivity
1118:Equation of state
966:Flash evaporation
918:Phase transitions
903:String-net liquid
796:Photonic molecule
766:Degenerate matter
599:Joost A. Businger
173:{\displaystyle d}
21:superheated water
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1184:Phases of matter
1108:Compressed fluid
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688:States of matter
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643:. Archived from
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470:amount of time.
442:nucleation sites
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85:nucleation sites
58:higher than its
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1098:Baryonic matter
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886:Antiferromagnet
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647:on 2 June 2008.
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518:Supersaturation
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480:bubble chambers
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305:
304:. So we obtain
273:
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127:surface tension
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54:is heated to a
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1194:Fluid dynamics
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1077:Trouton's rule
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946:Critical point
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848:Liquid crystal
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60:boiling point
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48:boiling delay
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37:
30:
26:
22:
1158:Superheating
1157:
1031:Vaporization
1026:Triple point
1021:Supercooling
986:Lambda point
936:Condensation
853:Time crystal
831:Other states
771:Quantum Hall
645:the original
614:
593:
582:
573:
547:
538:
513:Supercooling
498:Boiling chip
477:
474:Applications
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404:
221:
135:
131:
124:
113:
89:
74:
67:
47:
43:
40:superheating
39:
33:
1067:Latent heat
1016:Sublimation
961:Evaporation
896:Ferromagnet
891:Ferrimagnet
873:Dark matter
805:High energy
92:microwaving
81:homogeneous
56:temperature
25:superheater
1178:Categories
1082:Volatility
1045:Quantities
1006:Regelation
981:Ionization
956:Deposition
908:Superglass
878:Antimatter
812:QCD matter
791:Supersolid
786:Superfluid
749:Low energy
530:References
523:Subcooling
458:nucleation
69:metastable
62:, without
493:Autoclave
413:Δ
385:−
377:∝
371:Δ
348:π
345:∝
321:π
312:Δ
271:π
265:×
259:Δ
236:π
233:∝
202:−
194:∝
188:Δ
145:Δ
76:metastate
1143:Spinodal
1091:Concepts
971:Freezing
609:, pg 60.
486:See also
467:nitrogen
1103:Binodal
991:Melting
926:Boiling
843:Crystal
838:Colloid
446:flashes
64:boiling
731:Plasma
712:Liquid
605:
463:oxygen
52:liquid
721:Vapor
707:Solid
700:State
450:steam
102:Cause
96:burns
71:state
46:, or
692:list
603:ISBN
465:and
717:Gas
574:FDA
448:to
219:.
73:or
34:In
1180::
719:/
572:.
560:^
482:.
402:.
98:.
38:,
694:)
690:(
680:e
673:t
666:v
576:.
416:p
388:1
381:d
374:p
351:d
342:)
339:4
335:/
329:2
325:d
318:(
315:p
292:)
289:4
285:/
279:2
275:d
268:(
262:p
239:d
230:F
205:1
198:d
191:p
168:d
148:p
31:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
