The best way to know how to use them is to perform dimensional analysis to make sure that your units are cancelling out correctly. The units for R = 8.314 is J/K*mol and R = 0.08206 is L*atm/K*mol. Luckily, you won't need to memorize the units for this class, since they are given on the constant/formula sheet we are meant to use for midterms and the final.

Typically though, whenever you need an R value to use with the ideal gas equation (PV=nRT), then R=0.08206 will be the one needed (you technically could use R=8.314 but then you would need to convert from J to L*atm making it unnecessarily complicated). Meanwhile, other uses of R like in the work done by a reversible, isothermal reaction

(w=-nRTln(V2/V1) or standard Gibb's Free Energy (delta)G = -RTln(K) will utilize R=8.314.

I like to think about it that whenever Joules are involved (like in W or G), then R=8.314 is immediately the R I gravitate towards, and then if there are no units of Joules, then I start to look into the other options (like R=0.08206).

## FAQs

Depending on where you live and the part of your home you're insulating (walls, crawlspace, attic, etc.), you'll need a different R-Value. **Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces**.

**
How do I decide whether to use 0.0821 or 8.314 for R? ›
**
The units of measurement being utilised affect the value of R. When dealing with energy units, molar amounts, and Kelvin temperature, the value 8.314 J/(molK) is utilised in SI units. In non-SI units, especially when dealing with litres, atmospheres, and mol K, the value 0.0821 L atm/mol K is utilised.

**
How to choose the value of R? ›
**
**If you are using all other values in SI units (e.g. Pressure in Pa, Volume in m^3 and Temperature in K) then you should use R=8.314 J/mol/K**. But if you are taking Pressure in atm unit, volume in L and Temperature in K then you should use R=0.0821 L-atm/mol/K.

**
How do you choose which R-value to use in your equation? ›
**
The variable that determines which "R" value to use in a calculation is **pressure (P)**. The ideal gas law equation, PV = nRT, includes the universal gas constant (R), which has different values depending on the units used for pressure. If pressure is measured in atmospheres (atm), the value of R is 0.08206 L·atm/mol·K.

**
How to know what R-value to use in chemistry? ›
**
It is crucial to **match your units of Pressure, Volume, number of mole, and Temperature with the units of R**. If you use the first value of R, which is 0.082057 L atm mol^{-}^{1}K^{-}^{1}, your unit for pressure must be atm, for volume must be liter, for temperature must be Kelvin.

**
Which R do you use in PV nRT? ›
**
The ideal gas law is PV = nRT, where n is the number of moles, and R is universal gas constant. The value of R depends on the units involved, but is usually stated with S.I. units as: **R = 8.314 J/mol**. It is just a constant to use in the equation.

**
What is 0.08206 in chemistry? ›
**
The value of **R (Universal gas constant**) in SI unit is 0.08206 Latm/mol/K.

**
How do you select the lowest value in R? ›
**
In R, we can find the minimum or maximum value of a vector or data frame. We use the min() and max() function to find minimum and maximum value respectively. **The min() function returns the minimum value of a vector or data frame**.

**
Why do we find the R value? ›
**
R represents the value of the Pearson correlation coefficient, which is **used to note strength and direction amongst variables**, whereas R2 represents the coefficient of determination, which determines the strength of a model.

**
How to compare two values in R? ›
**
We can **use the compare package in R**. We can easily use this package to compare two data frames and check out the summary of what extent it is changed. The function comparedf() is used to compare two dataframes in R. The function takes two dataframes and then check them for comparison.

The ideal gas constant is the same for all gases but can vary based on which units are being used, the most common expressions are R = 0.0821 (L • atm/ mol • K) OR R = 8.31 (J/ mol • K). Each of the four variables ( within the ideal gas law formula) can be solved interchangeably while **R will always stay constant**.

**
Do you want a higher or lower R-value? ›
**
Typically, **a higher insulation R rating means better climate control and better energy efficiency for your home**. A higher insulation R-value usually means a higher price point as well. For every type and material of insulation, check the R-value per inch of thickness that the manufacturer has listed.

**
What is your R-value? ›
**
R-Value is **a measure of insulation's ability to resist heat traveling through it**. The higher the R-Value the better the thermal performance of the insulation. The table below shows what levels of insulation are cost-effective for different climates and locations in the home.

**
What does each R-value mean? ›
**
The R-value for insulation is **a way to measure how much resistance the insulation has to heat flow**. The higher the R-value, the more the resistance and the better the material is at insulating a home.

**
How do you determine which R value to use in a gas law problem? ›
**
You will choose the R value **based off of the units for the known quantities in the problem**. The key is usually pressure.

**
What determines the value for the gas constant R? ›
**
The value of the gas constant 'R' depends on **the units used for pressure, volume and temperature**. Prior to 2019, these were common values for the gas constant. In 2019, the SI base units were redefined. Both Avogadro's number and the Boltzmann constant were given exact numerical values.

**
When using the ideal gas law the correct value of R must be used? ›
**
Expert-Verified Answer

The value of R is **0.0821 L atm/mol K when the unit for pressure is atm**. The formula is PV = nRT, where P represents the pressure, V represents the volume, n represents the number of particles of the gas, R represents the ideal gas constant, and T represents the temperature.