Homework Problem 4C.13

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105311039
Posts: 107
Joined: Fri Aug 02, 2019 12:16 am

Homework Problem 4C.13

Postby 105311039 » Sat Feb 08, 2020 1:10 am

For this question, I am confused on why you add the the energy to melt the ice into the MCAT equation? I've never seen a question use this concept and just confused on it.

KnarGeghamyan1B
Posts: 102
Joined: Fri Aug 09, 2019 12:15 am

Re: Homework Problem 4C.13

Postby KnarGeghamyan1B » Sat Feb 08, 2020 1:35 am

To go from 0 degrees ice to 45 degrees liquid water, we must first go from 0 degrees ice to 0 degrees liquid water, which required an enthalpy of formation calculation. We can then use mCdeltaT to find the heat necessary to go from liquid water at 0 to the final temperature.

CalvinTNguyen2D
Posts: 102
Joined: Thu Jul 25, 2019 12:16 am

Re: Homework Problem 4C.13

Postby CalvinTNguyen2D » Sun Feb 09, 2020 4:46 pm

The problem asks for us to convert 0 degrees C ice into 45 degrees water. However, to do this, we need to melt the ice into water, which requires us to use the enthalpy of formation and a phase shift calculation. After that, we can calculate the energy required to heat 0 degrees water to 45 degrees water without further issue.

205154661_Dis2J
Posts: 109
Joined: Wed Sep 18, 2019 12:21 am

Re: Homework Problem 4C.13

Postby 205154661_Dis2J » Sun Feb 09, 2020 11:53 pm

It is very helpful to draw the graph. We see that in order to melt ice, we need to go through the plateau on the heating curve that turns a solid into liquid. So we have to include that in our calculations .


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