closed vs isolated

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Ekayana Sethi 2K
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closed vs isolated

Postby Ekayana Sethi 2K » Sat Feb 10, 2018 11:28 am

Are the pressures and volumes constant in a closed and isolated system?

Rachel Lu_dis1H
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Re: closed vs isolated

Postby Rachel Lu_dis1H » Sat Feb 10, 2018 11:32 am

I don't think they are unless it says otherwise. I do know that if it's a bomb calorimeter volume stays constant

SitharaMenon2B
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Re: closed vs isolated

Postby SitharaMenon2B » Sat Feb 10, 2018 1:54 pm

No, specifying the system as closed or isolated doesn't mean that the pressure or volume are constant.

Justin Folk 3I
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Re: closed vs isolated

Postby Justin Folk 3I » Sat Feb 10, 2018 3:08 pm

No, closed is just where matter can't escape. isolated is where neither matter nor internal energy can escape

Michelle Lee 2E
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Re: closed vs isolated

Postby Michelle Lee 2E » Sat Feb 10, 2018 11:25 pm

The text has to say if it is under constant pressure or volume. I don't think assuming is good enough.
I also have a question.
When the text says "ideal", does that mean constant pressure and volume because ideal would be 1 atm and 1M?

Xin He 2L
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Re: closed vs isolated

Postby Xin He 2L » Sun Feb 11, 2018 1:50 am

You don't want to assume anything, but if the question says that the reaction happens in a bomb calorimeter, you can assume it's constant volume.

Sarah 2F
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Re: closed vs isolated

Postby Sarah 2F » Mon Feb 12, 2018 1:22 pm

You can only assume that if the problem says so.

Alex Nechaev 1I
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Re: closed vs isolated

Postby Alex Nechaev 1I » Mon Feb 12, 2018 4:16 pm

Knowing whether a system is closed or isolated only tells you whether it can exchange energy with its surroundings or not. Don't assume that pressures and volumes are constant unless the problem specifically states that they are.

Annie Lieu-1H
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Re: closed vs isolated

Postby Annie Lieu-1H » Mon Mar 12, 2018 10:02 am

No, unless the problem specifies. When given just "closed" or "isolated" that deals with energy exchange (or lack thereof).

804899546
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Joined: Sat Jul 22, 2017 3:00 am

Re: closed vs isolated

Postby 804899546 » Fri Mar 16, 2018 10:24 pm

An example would be the expansion of a balloon. Say the pressure outside the balloon decreased, the volume of the balloon would increase as it expanded. However, it is still a closed system because the balloon never actually lost any matter, it just reacted to outside conditions.

Justin Folk 3I
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Re: closed vs isolated

Postby Justin Folk 3I » Fri Mar 16, 2018 11:00 pm

Does heat transfer happen when the balloon loses air?

Rachel N 1I
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Re: closed vs isolated

Postby Rachel N 1I » Sat Mar 17, 2018 12:37 pm

Yes, heat transfer does happens because they system is doing work and losing energy. This energy is replaced by heat flow, q, into the system.


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