Isolated system

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Johnathan Smith 1D
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Joined: Wed Sep 11, 2019 12:16 am

Isolated system

Postby Johnathan Smith 1D » Sun Feb 02, 2020 9:39 pm

Can someone give me an example of an isolated system that isn’t a bomb calorimeter and explain why it’s isolated?

EllieSchmidtke_4I
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Joined: Wed Feb 20, 2019 12:16 am

Re: Isolated system

Postby EllieSchmidtke_4I » Sun Feb 02, 2020 9:41 pm

An isolated system would be a closed, thermal-resistant water bottle (i.e. a Hydroflask). This is because both mass and heat energy cannot exit the system.

JohnWalkiewicz2J
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Re: Isolated system

Postby JohnWalkiewicz2J » Sun Feb 02, 2020 9:44 pm

You can think of a thermos as an isolated system as well! It can't exchange matter with its surroundings, and given its insulation, it can't exchange energy(heat) either!

Rafsan Rana 1A
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Re: Isolated system

Postby Rafsan Rana 1A » Sun Feb 02, 2020 9:44 pm

A system is considered isolated when the system cannot exchange energy/heat with its surroundings. An example would be a boiling water in a closed insulated container, like a hydroflask. This is considered an isolated system because the hot water in the container cannot exchange heat/energy with the environment because the insulated walls prevent that.

VLi_2B
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Re: Isolated system

Postby VLi_2B » Sun Feb 02, 2020 10:53 pm

Wait, but I assumed that heat would still technically be able to escape from a hydroflask to the surroundings. Are there any other examples that would be an isolated system?

chrisleung-2J
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Re: Isolated system

Postby chrisleung-2J » Sun Feb 02, 2020 10:55 pm

I believe that realistically a hydroflask would be considered a closed system, but in question 4A.1 it was established that a "very-high-quality thermos bottle" is an isolated system

Zoe Gleason 4F
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Re: Isolated system

Postby Zoe Gleason 4F » Sun Feb 02, 2020 10:56 pm

VLi_2B wrote:Wait, but I assumed that heat would still technically be able to escape from a hydroflask to the surroundings. Are there any other examples that would be an isolated system?

Heat isn’t supposed to be able to leave a hydroflask unless the lid is off. Another example of an isolated system is the universe, as energy is conserved.

SVajragiri_1C
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Re: Isolated system

Postby SVajragiri_1C » Sun Feb 02, 2020 11:09 pm

By definition an isolated system does not exchange matter or energy/heat with its surroundings. Most systems cannot be perfectly isolated, but can come very close. An insulated thermos with the lid screwed on tightly is an example of an isolated system, because the insulated prevents almost no heat or energy to be transferred to the surroundings, and no matter exchange.

Diana A 2L
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Re: Isolated system

Postby Diana A 2L » Sun Feb 02, 2020 11:48 pm

In terms of work and heat equations for energy exchanges between systems and their surroundings, do the equations we went over in Wednesday’s lecture apply to isolated systems? Or do we just not consider energy exchanges for isolated systems at all? IN OTHER WORDS, will we have any isolated system questions on the midterm?

Shail Avasthi 2C
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Re: Isolated system

Postby Shail Avasthi 2C » Mon Feb 03, 2020 5:37 pm

VLi_2B wrote:Wait, but I assumed that heat would still technically be able to escape from a hydroflask to the surroundings. Are there any other examples that would be an isolated system?


In reality, a hydroflask is a closed system. In theory, perfectly insulated thermos bottles would be isolated systems because they don't exchange energy with their surroundings.

Chris Charton 1B
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Re: Isolated system

Postby Chris Charton 1B » Mon Feb 03, 2020 6:10 pm

It's my understanding that a perfectly isolated system is theoretical and impossible to create. A thermos is an example of a practically isolated system- it exchanges energy at a slow enough rate to be considered isolated for a question.


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