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Author Topic: phase changes and phase diagrams  (Read 1181 times)

helen123

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phase changes and phase diagrams
« on: March 01, 2010, 08:08:07 PM »
hi! thanks for the help the other time. i really need help on this problem :-\

An ice cube tray contains enough water at 22.0°C to make 18 ice cubes that each have a mass of 30.0g. The tray is placed in a freezer that uses CF2Cl2 as a refrigerant. The heat of vaporization of CF2Cl2 is 158 J/g. what mass if CF2Cl2 must be vaporized in the refrigeration cycle to convert all water at 22.0°C at ice at -5.0°C? the heat capacities for H20(s) and H20(l) are 2.03 J/g•°C and 4.18 J/g•°C, respectively, and the enthalpy of fusion for ice is 6.02 kj/mol.

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phase changes and phase diagrams
« on: March 01, 2010, 08:08:07 PM »
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shengoc

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Re: phase changes and phase diagrams
« Reply #1 on: May 22, 2010, 10:44:30 AM »
Consider changes from
H2O(l) at 295 K ---> H2O(l) at 273K ---> H2O(s) at 273 K; this is phase change ---> H2O(s) at 268K

add all the enthalpy contribution from these changes, you are done

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Re: phase changes and phase diagrams
« Reply #1 on: May 22, 2010, 10:44:30 AM »
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