converting from pressure to concentration

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Vanessa Reyes_1K
Posts: 60
Joined: Fri Sep 28, 2018 12:28 am

converting from pressure to concentration

Postby Vanessa Reyes_1K » Sun Jan 13, 2019 11:49 am

When using the formula PV=nRT t convert between partial pressure and concentration, what is used for R? Is it a constant or should it be given in the problem?

Sophia Diaz - Dis 1B
Posts: 73
Joined: Fri Apr 06, 2018 11:02 am
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Re: converting from pressure to concentration

Postby Sophia Diaz - Dis 1B » Sun Jan 13, 2019 11:55 am

R is a constant that I'm pretty sure will be given to you on an equations list when we take exams. You just have to be aware of which R you use since it changes depending on what you're using. Meaning, R = 0.08206 when we are using Liters and atm (which is what we are doing now), but R = 8.314 when we are using Joules.

Steven Garcia 1H
Posts: 79
Joined: Fri Sep 28, 2018 12:16 am

Re: converting from pressure to concentration

Postby Steven Garcia 1H » Sun Jan 13, 2019 2:35 pm

I noticed in a lot of the textbook example R was equal to 8.314 x 10^-2 L^- mol^- bar^- K^-

It has different variations in which it can be written depending on the desired units you need to cancel. I'm confident that the constant value will be provided on any exams.

uhedlund
Posts: 38
Joined: Wed Nov 15, 2017 3:03 am

Re: converting from pressure to concentration

Postby uhedlund » Sun Jan 13, 2019 5:12 pm

It is a constant that will probably be included in the equations list for tests.

Srikar_Ramshetty 1K
Posts: 64
Joined: Fri Sep 28, 2018 12:27 am

Re: converting from pressure to concentration

Postby Srikar_Ramshetty 1K » Sun Jan 13, 2019 5:22 pm

R is constant but has many values. The 2 common values are R = 0.0821 L·atm/mol·K or R = 8.3145 J/mol·K. It is important to know the difference because the units are different. At the moment we are working with the first one where atm = atmospheres.

Hope that helps!


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