How to claculate value of universal gas constant?

You must do an experiment in which you measure the values of ##P, V, n##, and ##T##.

The is

##color(blue)(bar(ul(|color(white)(a/a) PV = nRTcolor(white)(a/a)|)))" "##

where

##P## = the pressure ##V## = the volume ##n## = the number of moles ##R## = the Universal Gas Constant ##T## = the temperature

We can rearrange the to get

##R = (PV)/(nT)##

If you do an experiment in which you measure the values of ##P, V, n##, and ##T##, you can insert these values into the equation and calculate ##R##.

For example, repeated experiments show that at standard temperature and pressure (273.15 K and 1 bar), 1 mol of gas occupies 22.711 L.

You can use this information to evaluate ##R##.

##R = (PV)/(nT) = ("1 bar" × "22.711 L")/("1 mol × 273.15 K") = "0.083 145 L·atm·K"^"-1""mol"^"-1"##

If you use strictly SI units, then pressure is measured in pascals and volume is measured in cubic metres.

##R = (PV)/(nT) = (1.013 25 × 10^5 color(white)(l)"Pa" × 22.414× 10^"-3"color(white)(l) "m"^3)/"1 mol × 273.15 K" = "8.3145 Pa·m"^3"K"^"-1""mol"^"-1"##

Always make sure that you use the value of ##R## corresponding to the units that you are using for ##P## and ##V##.