heat capacity question

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So according to EK the specific heat of water at 100C and 1 atm is infinite and there is no change in temperature. It says "the temperature of water at 100C does not increase when heat is added, regardless of how much heat. Instead it turns into steam."

Basically, is it saying all the water would need to turn into steam before heat can be transformed into KE and raising the temperature again? It is hard to think of infinitely adding heat w/o any change to the temperature of the water/steam.

Thanks for helping me clarify this.

Best,

Verónica

 

[block15]

I don't have the EK chem/physics books, but yes it's saying that in order for the temperature to rise above 100C the water needs to be completely converted to steam. Really the thing to think about regarding heat capacity at phase transitions is to draw a graph or two of what is actually happening. For example:

http://www.chemistrytutorials.org/images/stories/matter/change_of_phase1.png

That shows temperature versus time given a constant amount of heat (q) applied. Flip it around and you get:

http://mcat-review.org/calorimetry.gif

Now, think about how heat capacity is defined. C = Q/(change in Temp). That means if you add any heat and the temperature doesn't change, then the heat capacity is infinite. Also, the same happens at other phase transitions.

Hope that helps.