quick jump menu Acids and bases -sl Acids and bases -hl Atomic theory -sl Atomic theory -hl Bonding -sl Bonding -hl Energetics -sl Energetics -hl Equilibrium -sl Equilibrium -hl Kinetics -sl Kinetics -hl Organic chemistry -sl Organic chemistry -hl Oxidation and reduction -sl Oxidation and reduction -hl Periodicity -sl Periodicity -hl Stoichiometry Higher physical organic Medicines and drugs Human biochemistry Environmental chemistry Chemical industries Fuels and energy Modern analytical chemistry Further organic chemistry
 syllabus return faq software forum contact add to favorites

These notes were written for the old IB syllabus (2009). The new IB syllabus for first examinations 2016 can be accessed by clicking the link below.

Universal gas constant R

This depends on the units of the measurements used in the ideal gas equation PV=nRT

R then equals PV/nT

If n equals one (for one mole of gas) then

R = PV/T

Using SI units

pressure is measured in Nm-2 and the value at atmospheric pressure is 1.01 x 105

temperature is measured in Kelvin = 273 at STP

volume in SI units 22.41 dm3 = 2.241 x 10-5 m3

R = PV/T = (1.01 x 105 x 2.241 x 10-5) /273

R = 0.00829

When P is measured in atimospheres, and V is measured in dm3

R = PV/T

R = 1 x 22.41 / 273

R = 0.0821