R Constant


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Alexis Robles 2k
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R Constant

Postby Alexis Robles 2k » Sun Jan 19, 2020 9:31 pm

What is the R constant in PV=nRT, I keep hearing there are different R constant and I am confused about that?

Donavin Collins 1F
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Re: R Constant

Postby Donavin Collins 1F » Sun Jan 19, 2020 9:33 pm

The gas constant, R, is 8.314 J/mol·K I believe.

Nicholas Chin 1G
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Re: R Constant

Postby Nicholas Chin 1G » Sun Jan 19, 2020 9:34 pm

The R constant is the universal gas constant, and the reason there are different values for it is because the units can vary, from atmospheres to barrs.

DHavo_1E
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Re: R Constant

Postby DHavo_1E » Sun Jan 19, 2020 9:36 pm

Alexis Robles 2k wrote:What is the R constant in PV=nRT, I keep hearing there are different R constant and I am confused about that?


Hello,

For the Ideal Gas Law (PV=nRT), R= 8.314J/molK, which is the universal gas constant. I believe there is also differing R constants depending on units used. I found the section "The Gas Constant (R)" on this website to be helpful!

https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/States_of_Matter/Properties_of_Gases/Gas_Laws/The_Ideal_Gas_Law

Jesalynne 2F
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Re: R Constant

Postby Jesalynne 2F » Sun Jan 19, 2020 9:45 pm

The R constant will be provided on the "Constants and Formulas" worksheet which can be found on the 14B class website and will be provided on tests and midterms, so we will not have to remember it. The constant can change depending on what units it is in, but different unit forms are also provided on the formula sheet.

cassidysong 1K
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Re: R Constant

Postby cassidysong 1K » Sat Jan 25, 2020 4:52 pm

There are different R constants that have different units so you just pick the R constant that has units matching the other parts (i.e. atm or bar)

Jasmine Vallarta 2L
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Re: R Constant

Postby Jasmine Vallarta 2L » Sat Jan 25, 2020 4:55 pm

The R constant differs depending on what units are used for pressure so we don't have to manually convert it

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

Re: R Constant

Postby 205389184 » Sun Jan 26, 2020 8:16 pm

There are different values for the constant R but that is only because it depends on the units that are being used, but they will be provided on the equation sheet that is given on the tests.

Chris Charton 1B
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Re: R Constant

Postby Chris Charton 1B » Sun Jan 26, 2020 8:24 pm

R is the gas constant. It has different values depending on what units you are using.

Anish Natarajan 4G
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Re: R Constant

Postby Anish Natarajan 4G » Sun Jan 26, 2020 8:27 pm

There are different values for R depending on the units that you are using in your calculations

AronCainBayot2K
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Re: R Constant

Postby AronCainBayot2K » Sun Jan 26, 2020 8:32 pm

R constants are given and should be applied based on the units given in the problem. Pressure is the unit to look for as it determines which R constant to plug ig to PV = nRT

Anna Chen 1K
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Re: R Constant

Postby Anna Chen 1K » Sun Jan 26, 2020 9:54 pm

The R constant is the gas constant. Its value is determined by the units in the specific problem.

Charysa Santos 4G
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Joined: Wed Sep 18, 2019 12:21 am

Re: R Constant

Postby Charysa Santos 4G » Sun Jan 26, 2020 10:02 pm

The R depends on what other units you are working with in your PV = nRT calculation.

Mandeep Garcha 2H
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Joined: Sat Aug 24, 2019 12:17 am

Re: R Constant

Postby Mandeep Garcha 2H » Sun Jan 26, 2020 10:10 pm

The R constant is given on the sheet of constants and equations for the test, so you will not need to memorize it( but familiarize yourself with it).

Rosa Munoz 2E
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Re: R Constant

Postby Rosa Munoz 2E » Mon Feb 10, 2020 8:54 am

Look at the units to decide which one to use

Donna Nguyen 2L
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Joined: Sat Aug 24, 2019 12:17 am

Re: R Constant

Postby Donna Nguyen 2L » Tue Feb 11, 2020 1:09 am

In many of our examples and homework problems, the R constant is 8.314 J/mol·K, but if you look at Dr. Lavelle's constants and equations sheet, R is the gas constant and actually has different values. The R value you use depends on the units that are given in the problem.

alex_4l
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Joined: Thu Sep 26, 2019 12:18 am

Re: R Constant

Postby alex_4l » Tue Feb 11, 2020 1:12 am

8.314 J/mol·K is the most common used form for the R gas constant, but there are other types of numbers given for it depending on the units. I would suggest memorizing this number just in case the formula sheet has a different value on it since this is the most common used form of it used in our problems

WGaines_2E
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Joined: Mon Nov 18, 2019 12:18 am

Re: R Constant

Postby WGaines_2E » Tue Feb 11, 2020 10:22 am

when using pv=nrt r is usually 8.314 J/molK but its gonna be given on the exam

CameronDis2K
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Re: R Constant

Postby CameronDis2K » Wed Feb 12, 2020 1:35 pm

Correct, there are 3 different R values depending on the units that are presented to you, such as atm or torr. But they all are equivalent to each other (even though their units are somewhat different(.


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