Difference Between Boiling Point and Melting Point

Main Difference – Boiling Point vs. Melting Point

Melting point and boiling point both describe temperatures at which phase changes occur in substances. The main difference between boiling point and melting point is that the melting point is defined as the temperature at which solid and liquid phases are in equilibrium, whereas the boiling point is the temperature at which the vapour pressure of a liquid is equal to the external pressure.

Difference Between Boiling Point and Melting Point - Melting and Boiling

Difference Between Boiling Point and Melting Point – Melting and Boiling

What is Melting Point

Melting point is defined for a substance as the temperature at which its solid and liquid phases can exist in equilibrium. It is at this temperature that a solid will start melting to  become a liquid. At this temperature, the molecules forming the substance are gaining enough kinetic energy to overcome the intermolecular forces which hold them in fixed positions and they gain the ability to move around. The freezing point describes the temperature at which a liquid can start forming a solid. A substance can be supercooled below its freezing point without it forming a solid, so technically, melting and freezing points are not the same. However, we can assume them to be almost the same for a wide variety of cases.

What is Boiling Point

Boiling point can be defined for a liquid as the temperature at which its vapour pressure is equal to external pressure. At this temperature, the substance in liquid phase enters the gas phase. If the external pressure is larger, then it takes a higher temperature for the vapour pressure to become equal to the external pressure. Consequently, the boiling point is highly dependent on external pressure. For instance, water can be boiled at much lower temperatures when the external pressure is lower (around 70o C at Mount Everest for example). The  normal boiling point is defined as the temperature at which the vapour pressure of the liquid is equal to 1 atm, i.e. the temperature at which liquid would boil when the external pressure is equal to 1 atm.

Difference Between Boiling Point and Melting Point

Definition of Boiling Point and Melting Point

Melting point is the temperature at which solid and liquid phases of a substance are in equilibrium.

Boiling point is the temperature at which its vapour pressure is equal to the external pressure.

Phase Change

At the melting point, a solid becomes a liquid.

At the boiling point, a liquid becomes a gas.

Pressure Dependence

Melting point does not change with changes in the external pressure.

Boiling point changes with changes in the external pressure.

Image Courtesy:
(Untitled) by Fotocitizen (Own work) [], via  (modified)
“Boiling Water” by Scott Akerman (Own work) [], via  (modified)

About the Author: Nipun

Related pages

what is a autotroph and a heterotrophdefine dejurewhat is the difference between persuade and convincecoordinating connectivesdifference between organelles and inclusionswhat is external respirationwhat does amoral meanpolar or nonpolar moleculesdefinition of dipole dipoletofu is paneerwhat are two differences between transcription and dna replicationwhat is the difference between evaporation and transpirationwhat is the relationship between absorbance and concentrationgolden retriever vs golden labpolar and nonpolar definitionfunction of stomatal poreelastic and gravitational potential energyisotropic and anisotropic solidsdistinction between phonetics and phonologydifferences prokaryotic and eukaryotic cellswhat is header and footer in computerwhat is the difference between bacteria and virusmaki vs sushiwhat are heterotrophs and autotrophsakita vs akita inutrade name for sodium bicarbonateexample acculturationwhats bicameralxylem and phloem differencewhat is the difference between a mile and a kilometerexamples of omniscientsharks mammal or fishcold sores vs canker soresgung po chickenenglish adverbialsexamples of positive and normative economicsalpha helices and beta pleated sheets are examples ofwhat is the difference between bronchitis and asthmadifference between diabetes insipidus and mellitusword enunciationradial symmetricalcushing syndrome vs cushing diseasewhat is enantiomers and diastereomerspink pummelodistinguish between aldehydes and ketonesdifference between crochet and knittingpecans and walnutscaesura poemdyspnea definegymnosperm fertilizationmountains plateaus and plains are types ofexamples of motif in literatureparboiling vegetablescapacitors and inductors in dc circuitsdifference between hair rebonding and hair smoothingwhat is the definition of unicameralenjambment literary definitionmeaning of cold blooded animalscathedral vs churchprotagonist and antagonist examplesseries and parallel resonance circuitsis baking soda the same as bicarb sodasimilarities between rain and dewgraveyard and cemetery differencesnuggle vs cuddlecalculating angle of reposeis factory a noundifference between pteridophytes and bryophytesdifference between potential transformer and power transformerwhat is bod & codwhat is the difference between denotation and connotationpositive and normative statements in economicsfructose and sucrose differencethermoset plastic examplesconceits examplesdifference between cytoplasm and cytoskeleton