Which R to Use? [ENDORSED]

[Justin An 2L]

How do you know which R gas constant to use when solving either PV=nRT or the integral equation? I got that mixed up on the last homework set (I know you can look at the units and see which cancel out, but I just wanna see if there's a different way)

[Chem_Mod]

Need to look at units to see which R value to use.

[Lindsay Beckwith 2B]

You have to know all the units involved to know which R to use. I always find it super helpful to write out the entire equation I am using including the units. This shows you which ones cancel out on their own, leaving you with which units the R value needs to be in to solve for the variable of interest.

[sadiebrebes]

Yes, you look wether it is using the units below:
Value Units
R 0.08206 L·atm/K·mol
R 8.3145 J/K·mol
R 1.9872 cal/K·mol

[raynebunado]

Look at the units and make sure to convert if asked in the question!

[Ally Mosher]

You have to look at the units and convert as necessary to use the correct R value. Make sure the units cancel!!

[JasmineReyes-2K]

Hi,
You would look at your given information and identify the corresponding units

[JasmineReyes-2K]

Hi,
You would look at your given information and identify the corresponding units

[Alexander Moroz 1B]

The equation/information given will tell you. For example, if using PV=nRT, you should use R=0.08206 because its units are L*atm/Kmol, which cancel out with the units of the equation.

[Charlie Gravereaux]

When choosing the gas constant value to use, just look at the other units being used in the equation, as you will want the gas constant to match up to these units in order to eventually cancel out. On the equation sheet, the units for each R value are given, so you can easily determine from there.

[Gianna Greco 1G]

It depends on which units you are using! Here are the different values depending on the units: R 0.08206 L·atm/K·mol, R 8.3145 J/K·mol, R 1.9872 cal/K·mol

[Aaron Kim 1J]

You should make note of what units you're working with and what you're trying to find. In most cases, the units that are present would be cancelled out by the units of the R you're using.

[Julie Mai 1K]

To determine which R value to use, I usually look at what units are given.

[ajguerrero]

It mainly depends on what units you're working with to determine what R to use.

[Jessica Li 1G]

I decide which R value to use based on the given units in the problem at hand, and then determining which R value covers all of the units involved.

[Julia Todorov 2F]

you have to look at the units to know which R to use, but from what I've noticed most of the times when you are using it in PV=nRT then its the .082 R and then the integral equations usually use the 8.314 one

[Joseph Lee]

Whenever pressure comes into play, make sure you're using the 0.08206 with atm, but if not, it is usually referring to 8.314 value. Just make sure to look at the units and seeing if they properly cancel each other out. I know it seems like a lot of work but it does help make you gain confidence.

[Sean Sanders 1E]

The best way to determine which R to use it to determine the units needed in the solution.

[Celine_Nguyen_3K]

You need to look at the units that you have in order to figure out the correct ideal gas constant to use. As long as you keep your units consistent throughout the problem, you're good.

[Nandini_Parmar_1I]

Depending on the units depends on what R to use.

[andrea tarelo 3e]

I like to look at the units given and then base which r I use from that. These are the values that I typically use on the homework and practice problems.
R = 8.31 J mol-1 K-1
R = 0.0821 L atm mol-1 K-1

[Brenda Tran 3C]

I don't think there is another way other than looking at the units since you want certain things to cancel out.

[105740916]

Look at the units in the question and use the according R value

[Kayla Ziebell 1H]

It all depends on the units! You want certain units to be able to cancel out with the other factors in the equation, so you chose the R value that does that.

[Julia Zahra]

You need to look at the units to decide which one works the best.

[jaycmartinezDisc3b]

Hello! In order to figure out which R to use, you need to pay attention to the units you are dealing with. This will make it so that most of the units you are using will canceled out, giving the units of whatever you want to solve for in the ideal gas equation.

[Lindsey Walter 3E]

You will decide which R-value to use based on the units you are trying to find/use in the problem.

[Hana Aflatooni]

Look at the units and make sure to use the R value that has the same units as the question

[Aneesha_Nema_3C]

It's entirely based on the units of the variables in the equation. Just pay attention to which unit is being used in the problem and use the corresponding value of R.

[Parinita Jithendra 2A]

to find the right r-value, it is completely based on the units. U can convert it at the beginning or at the end. But it would be better to do it in the beginning so that you don't need to make extra calculations

[405716590]

thank you this is all very helpful