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Why does it take more energy for a phase change to occur from a liquid to gas than a solid to liquid?

Posted: Sat Feb 04, 2017 10:27 pm
by Ace 3F
Looking at the phase diagram: http://www.sciencegeek.net/APchemistry/APtaters/graphics/phasediagram2.gif

It is clear that Leg B is smaller than Leg D, what is the reason behind this?

Re: Why does it take more energy for a phase change to occur from a liquid to gas than a solid to liquid?

Posted: Sat Feb 04, 2017 10:39 pm
by Arianna_Mandelli_3C
Within the phase change from solid to liquid, the bonds between atoms are merely loosened. In the phase change from liquid to gas, the bonds between atoms are completely broken. The phase change from liquid to gas requires more energy because the bonds must be completely broken for it to take place, rather than just loosened as in the phase change of solid to liquid.

Re: Why does it take more energy for a phase change to occur from a liquid to gas than a solid to liquid?

Posted: Sun Feb 05, 2017 5:07 pm
by Aaron_Trell_2J
Also, if you want to associate this change with a real world example just think about the process of boiling water vs melting ice. It is much easier to melt ice if heat is applied to it while it takes a much longer time to completely vaporize the same mass of water.