Constant pressure

isochoric/isometric:
isothermal:
isobaric:

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Rosa Munoz 2E
Posts: 105
Joined: Wed Sep 18, 2019 12:21 am

Constant pressure

Postby Rosa Munoz 2E » Sun Feb 02, 2020 1:06 pm

When they refer to constant pressure, are we referring to constant external pressure?

Sahil Jog 1F
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Joined: Thu Jul 11, 2019 12:16 am

Re: Constant pressure

Postby Sahil Jog 1F » Sun Feb 02, 2020 1:11 pm

Yes they are referring to constant external pressure, since a dynamic external pressure would do unnecessary work on a system, and thus be unreasonable problem to solve.

faithkim1L
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Joined: Fri Aug 09, 2019 12:17 am

Re: Constant pressure

Postby faithkim1L » Sun Feb 02, 2020 1:21 pm

Constant external pressure.

Vinita Saxena 2I
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Joined: Fri Aug 09, 2019 12:16 am

Re: Constant pressure

Postby Vinita Saxena 2I » Sun Feb 02, 2020 1:38 pm

Yes, constant external pressure

Callum Guo 1H
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Re: Constant pressure

Postby Callum Guo 1H » Sun Feb 02, 2020 1:38 pm

Constant external pressure

205389184
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Joined: Sat Sep 07, 2019 12:18 am

Re: Constant pressure

Postby 205389184 » Sun Feb 02, 2020 11:22 pm

Yes, you are correct, we are referring to constant pressure

Jacob Villar 2C
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Re: Constant pressure

Postby Jacob Villar 2C » Sun Feb 02, 2020 11:28 pm

Constant external pressure.

Alexis Robles 2k
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Joined: Wed Sep 18, 2019 12:18 am

Re: Constant pressure

Postby Alexis Robles 2k » Mon Feb 03, 2020 12:06 am

yeah, its Constant external pressure.

rohun2H
Posts: 100
Joined: Wed Sep 18, 2019 12:19 am

Re: Constant pressure

Postby rohun2H » Mon Feb 03, 2020 12:39 pm

Yes, constant external pressure.

705367472
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Joined: Tue Nov 19, 2019 12:19 am

Re: Constant pressure

Postby 705367472 » Wed Feb 05, 2020 11:54 pm

yes, we are referring to constant external pressure

Matt Sanruk 2H
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Re: Constant pressure

Postby Matt Sanruk 2H » Wed Feb 05, 2020 11:57 pm

And this would be irreversible?

Adriana_4F
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Joined: Fri Sep 28, 2018 12:29 am

Re: Constant pressure

Postby Adriana_4F » Thu Feb 06, 2020 12:04 am

Matt Sanruk 2H wrote:And this would be irreversible?


Yes this would be irreversible

Radha Patel 4I
Posts: 97
Joined: Tue Feb 12, 2019 12:15 am

Re: Constant pressure

Postby Radha Patel 4I » Thu Feb 06, 2020 7:38 am

It would be irreversible and it would be referring to external pressure so w=0

aishwarya_atmakuri
Posts: 101
Joined: Sat Jul 20, 2019 12:15 am

Re: Constant pressure

Postby aishwarya_atmakuri » Thu Feb 06, 2020 11:17 am

Yes, they would be referring to a constant external pressure.

CameronDis2K
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Joined: Wed Feb 20, 2019 12:18 am

Re: Constant pressure

Postby CameronDis2K » Fri Feb 07, 2020 3:00 pm

Yes, constant external pressure, as it allows the system to change somewhat independent of the external environment. For example, in the equation for an irreversible expansion work, W = - P external * delta V. However, if it is a gas in a container, pressure of the gas may be determined through the ideal gas law (but the system pressure will change).

KBELTRAMI_1E
Posts: 108
Joined: Sat Jul 20, 2019 12:17 am

Re: Constant pressure

Postby KBELTRAMI_1E » Fri Feb 07, 2020 3:56 pm

Is it always assumed to be 1 atm? What about in a vacuum?

Vinita Saxena 2I
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Joined: Fri Aug 09, 2019 12:16 am

Re: Constant pressure

Postby Vinita Saxena 2I » Sun Feb 09, 2020 12:39 am

In a vacuum there is no external pressure, so there is nothing to push back against, meaning w=0

Micah3J
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Joined: Tue Oct 08, 2019 12:16 am

Re: Constant pressure

Postby Micah3J » Sun Feb 09, 2020 12:45 am

And so just because there is constant external pressure, the internal pressure can still be changing because of the reaction going on?

RobertXu_2J
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Joined: Fri Aug 30, 2019 12:17 am

Re: Constant pressure

Postby RobertXu_2J » Sun Feb 09, 2020 2:12 am

Yes, constant external pressure.

Mulin_Li_2J
Posts: 105
Joined: Sat Aug 17, 2019 12:16 am

Re: Constant pressure

Postby Mulin_Li_2J » Sun Feb 09, 2020 6:36 pm

Yes and I can give you some explanation on this.

You might refer to "constant pressure" mentioned when we try to calculate the amount of work done by a system. First, let's take a look at the definition of work: w = F(o)*D. F(o) here refers to an opposing force. Basically, this formula implies that you have to have an opposing force to do work, and the work you have done is how far you got by pushing against the opposing force. Hence, because w = -P*deltaV is a derived formula from w = F(o)*D, P also refers to external pressure.

Hope this can help! -_+


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