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Topic: Help on changes of physical state problem  (Read 4144 times)

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Offline JimJo

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Help on changes of physical state problem
« on: December 03, 2007, 12:10:42 AM »
I am doing practice problems and there is no answer to this question and i am not sure if i am right.

The problem is, Calculate the amount of heat released when 90.5g of steam at 110.0 Celsius cools to ice at 0.0 Celsius.

The answer i got was 48870+9955+7240 = 66065 cal. Is that correct?
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Offline Padfoot

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Re: Help on changes of physical state problem
« Reply #1 on: December 03, 2007, 01:13:06 AM »
Method looks OK. 
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Offline enahs

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Re: Help on changes of physical state problem
« Reply #2 on: December 03, 2007, 09:40:56 AM »
You have three energy values, but there should be four.

Cool the steam from 110C  to 100 C. The energy required for the transition of the Steam to Water. The energy to cool to water from 100 C to 0C. But you then also need the energy to transition the liquid water at 0 C to Ice at 0 C.

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Offline Padfoot

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Re: Help on changes of physical state problem
« Reply #3 on: December 03, 2007, 05:26:52 PM »
Quote from: enahs on December 03, 2007, 09:40:56 AM
You have three energy values, but there should be four.
It looks as if he has combined the 2 steps in which temperature is changing.  I checked  :)
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