## Constant Pressure/Volume

Layal Suboh 1I
Posts: 61
Joined: Fri Sep 28, 2018 12:23 am

### Constant Pressure/Volume

Hello,

Dr. Lavelle went over a question in class last week that said "an exothermic reaction occurs an open beaker producing a net 8 moles of gas at 25 C. What is the change in internal energy?"

How do we know that this reaction is occurring under conditions of constant pressure?

Thanks!

ariana_apopei1K
Posts: 89
Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

### Re: Constant Pressure/Volume

Hi, I just checked my notes and i wrote "assume P=1 atm, use PV=nRT), meaning the pressure is constant at 1 atm. Maybe he only said this verbally or something and it wasn't on the slides and you might have missed it? I hope this helps!

Kelsey Warren 1I
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

### Re: Constant Pressure/Volume

Also, the pressure has to be constant in an open beaker because the pressure in the beaker would equal the atmospheric pressure, which is constant.

Henry Dudley 1G
Posts: 61
Joined: Fri Sep 28, 2018 12:16 am

### Re: Constant Pressure/Volume

If the pressure is not stated, it is assumed to be 1 atm. So in this case, it is assumed that the pressure is constant at 1 atm.

Abby-Hile-1F
Posts: 46
Joined: Fri Sep 28, 2018 12:16 am

### Re: Constant Pressure/Volume

So if pressure is not given, can we assume that it will remain constant at 1 atm?

Cameron_Greenberg_3C
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

### Re: Constant Pressure/Volume

"Open beaker" implies constant pressure of 1 atm.

Fionna Shue 4L
Posts: 59
Joined: Fri Sep 28, 2018 12:18 am

### Re: Constant Pressure/Volume

If the reaction is taking place in an open beaker, pressure will be constant

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