Latent heat Latent heat: amount of energy needed to add or to remove from a substance to change the state of that substance Phase change: T remains constant but internal energy changes heat does not result in change in T(latent ="hidden) e.g.: solid o> liquid or liquid o gas heat goes to breaking chemical bonds n Heat per unit mass [L=J/kg Q=±mL stea if heat needed(boiling) if heat given(freezing) lce. Lf: Latent heat of fusion 2000 solid o liquid 30703110 nenx ade (一 Ly: Latent heat of vaporization liquid o gas Lf(J/kg) Lv(J/kg) water335×10422.6×105 Physics 121: Lecture 25, Pg 5Physics 121: Lecture 25, Pg 5 Latent Heat L = Q / m Heat per unit mass [L] = J/kg Q =  m L + if heat needed (boiling) - if heat given (freezing) Lf : Latent heat of fusion solid  liquid Lv : Latent heat of vaporization liquid  gas Latent heat: amount of energy needed to add or to remove from a substance to change the state of that substance. Phase change: T remains constant but internal energy changes heat does not result in change in T (latent = “hidden”) e.g. : solid  liquid or liquid  gas heat goes to breaking chemical bonds Lf (J/kg) Lv (J/kg) water 33.5 x 104 22.6 x 105