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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: rinks on July 14, 2009, 05:18:02 PM

Title: Phase Changes
Post by: rinks on July 14, 2009, 05:18:02 PM

Hi I need help with a homework question:

Consider an insulated system containing 100 g of liquid water and 100 g of ice at equilibrium under atmospheric pressure. A total of 12 g of steam at 110C is admitted to the system. What is the phase composition and temperature when equilibrium is reestablished?

I'm not sure where to start first...

Title: Re: Phase Changes
Post by: calciumoxide on July 14, 2009, 06:47:06 PM

Well you know the system is under a physical equilibrium of water (liquid <-> solid), so you can assume the temperature of the system is at freezing point. Now when you add the 12 g of steam at 110C, what will happen? Notice the question is set under constant pressure (atm pressure), so you can set  :delta:H = q. What is the equation for q? Another hint is that you also have to consider  :delta:H fusion/freezing of water. Hope this helps.