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What islatentheat ?Give is unitswith the helpof asuitablegraph , explainthetermslatentheatof fusion latentheat ofvaporisation. |
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Answer» ` Solution :latent heat:The amountof heattransferredper unitmas duringthechangeof phaseof asubstancewithoutany changein itstemperatureis calledlatentheat of thesubstanceforparticularchange  Latentheatis denotedby Land havingSI, (i)LATENTHEAT offusion : It islatentheat forsolid -liquidstatechangeit isdenotedby Lfand is givenby latentheatof fusionLf `= (Q)/(m)` ItSI unitis `jK^(-1)` (ii) latentheat ofvaporisation : It islatentheat for liquid- gaschangeIt isdenotedby L v andoftenreferredto asheatof fusionand heatofvaporisation. Itis givenby Latentheat ofvaporisatin `L_(v)= (Q)/(m)`and its SIunitis`J KG^(-1)` startingapointA thesubstanceis initssolidphasaeheatingitbringsthe temperatureup toitsmeltingpointbut thematerialis stilla solidatpoint B. As it is heatedfurtherthe energyfrom theheatsourcegoesintobreaking thebondsholdingthe atomsisplace. Thistakesplace from Bto C.AtpointCallof the solidphasebeentransformedintothe liquidphase. Onceagainasenergyis added theenergygoes intothe KINETICENERGYOF theparticlesraisingthetemperature(C to D). AtpointD thetemperaturehasreached itsboilingpointbutit isstillintheliquidphase. frompointsD TOE thermalenergyis overcomingthe bondsand theparticleshaveenoughkineticenergyto escape FROMTHE liquidthe substanceis enteringthe gasphase. BeyondE, Furtherheatingunderpressurecan raisethe temperaturestillfurtheris howa pressurecookerworks . |
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