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Nina Gautam 1K
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Joined: Fri Sep 29, 2017 7:04 am


Postby Nina Gautam 1K » Wed Jan 24, 2018 10:02 pm

For question 8.41, I was wondering why the volume of water in the calculation wouldn't change from 400g to 450g? The question asks for the final temperature of the system, so wouldn't that imply that the ice cube completely melts into the water and increases the mass of liquid H2O?

Alyssa Parry Disc 1H
Posts: 53
Joined: Sat Jul 22, 2017 3:01 am

Re: 8.41

Postby Alyssa Parry Disc 1H » Wed Jan 24, 2018 10:09 pm

This is because you are calculating the two things, the ice that melts into water and the liquid water that you started with, separately.

Kayla Danesh 1F
Posts: 38
Joined: Thu Jul 13, 2017 3:00 am

Re: 8.41

Postby Kayla Danesh 1F » Thu Jan 25, 2018 5:05 pm

If you remember Dr. Lavelle's lecture slide from class, is said that "qsys=-qsurroundings." In this case, you can kind of think of the ice as the "system" and the water is the "surroundings." So, you would set the heat needed to melt the ice+the heat needed to raise the temperature of the ice equal to the heat lost by the surrounding water. But, you are correct that the final answer asks you for the heat of the system, which does include both the ice and the water. The Tfinal of the water and the ice will be the same though, which will give you your final answer.

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