Asked by Caleb

How much heat is evolved in converting 1.00 mol of steam at 155.0 ∘C to ice at -45.0 ∘C? The heat capacity of steam is 2.01 J/(g⋅∘C) and of ice is 2.09 J/(g⋅∘C).

Answers

Answered by DrBob222
Let's see if you can do this yourself.
heat at phase change is
q = mass x heat vaporization at boiling point or
q = mass x heat fusion at freezing point.

Between phases it is
q = mass x specific heat x (Tfinal-Tinitial).
Now you have steam at 155 so it must go "within the phase" to 100 so that is equation 3.
Then you change from steam vapor to steam liquid. That's a phase change at the boiling point. Use equation 1.
Then you change T from 100 to zero C. That's equation 3 again.
At zero it freezes so that's a phase change from liquid to solid and you use equation 2.
Then you go from zero with a solid to -45 with a solid. That's equation again.
Then add all of the q values together.
Answered by Caleb
I'm still not getting the correct answer.
Answered by Caleb
I'm getting 5.65 kJ
Answered by DrBob222
Post your work for each step and I'll check it.
Answered by DrBob222
Check your arithmetic. I It looks like you have the right digits (close anyway) but off by a factor of 10. You don't show what you're using for delta H vap or delta H fusion. I used 18 g for a mole of H2O, 334J for delta H fusion and 2257J for heat vap and 4.18 for specific heat liquid water.
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