R constant in PV=nRT


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DesireBrown1J
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Joined: Wed Sep 18, 2019 12:18 am

R constant in PV=nRT

Postby DesireBrown1J » Wed Jan 08, 2020 6:04 pm

What exactly is the ideal gas constant in R? When I looked it up, I realized that there are two different ones to use. How do we determine which one to use based on what information is given to us in a problem?

AlyshaP_2B
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Re: R constant in PV=nRT

Postby AlyshaP_2B » Wed Jan 08, 2020 6:06 pm

I think the gas constant will be given to us either in the question or on an equation sheet!

nehashetty_2G
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Joined: Thu Jul 25, 2019 12:15 am

Re: R constant in PV=nRT

Postby nehashetty_2G » Wed Jan 08, 2020 6:07 pm

I think it will most likely by R=8.314 J/(Kmol) because that is what Lavelle gave on the formula/constant sheets in 14A. In general just look at the units to figure out what to use, or to see if you need to manipulate the constant.

Areli C 1L
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Re: R constant in PV=nRT

Postby Areli C 1L » Wed Jan 08, 2020 6:10 pm

Most likely it will be R=8.314 J/(K*mol) as it will be cancelled out with T= Kelvin. Also it probably will be given in our constant sheet on exam days.

Natalie Benitez 1E
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Re: R constant in PV=nRT

Postby Natalie Benitez 1E » Wed Jan 08, 2020 6:35 pm

I believe the constant will be given to us in the constant sheet so what don't really need to worry about it.

Pablo 1K
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Re: R constant in PV=nRT

Postby Pablo 1K » Wed Jan 08, 2020 6:52 pm

You would check your units to see which one you would utilize!

Abigail_Hagen2G
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Re: R constant in PV=nRT

Postby Abigail_Hagen2G » Thu Jan 09, 2020 11:48 am

For homework though the one on the equation sheet should work

nicole-2B
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Re: R constant in PV=nRT

Postby nicole-2B » Thu Jan 09, 2020 3:27 pm

Gas constant, R = 8.314 J·K-1·mol-1 = 8.206 x 10-2 L·atm·K-1·mol-1 = 8.314 x 10-2 L·bar·K-1·mol-1= 62.364 L·Torr·K-1·mol-1
This is what was on the constants and formualas sheet on Dr. Lavelle's website.

Jocelyn Thorp 1A
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Re: R constant in PV=nRT

Postby Jocelyn Thorp 1A » Thu Jan 09, 2020 5:18 pm

DesireBrown1J wrote:What exactly is the ideal gas constant in R? When I looked it up, I realized that there are two different ones to use. How do we determine which one to use based on what information is given to us in a problem?


the way to determine which constant to use would be to look at the units and find which one matches! for example, if pressure is in pascals you would use the constant associated with that, or if it were in atm then you would use that one.

Uisa_Manumaleuna_3E
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Joined: Wed Sep 21, 2016 2:56 pm

Re: R constant in PV=nRT

Postby Uisa_Manumaleuna_3E » Thu Jan 09, 2020 7:08 pm

You don't have to worry too much though about which one of the R constant values to use, because (like everyone else said) the units will match up to the one we're supposed to use. So if you end up plugging in one of the other R values to the equation, not all of the units will cancel out and your answer will have some strange blend of every unit on the sheet. At least for me, that makes it pretty obvious that I chose the wrong one and have to go back a little.


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