What is gram molecular weight?
Gram molecular weight is the molecular weight (MW) expressed in grams. For example, the gram molecular weight for toluene is 92.13 g. since the molecular weight is 92.13. A gram molecular weight is also called a gram mole. How do I convert mg/m3 to ppm at different temperatures and pressures? The number 24.45 in the equations above is the volume (liters) of a mole (gram molecular weight) of a gas or vapour when the pressure is at 1 atmosphere (760 torr or 760 mm Hg) and at 25°C. To convert mg/m3 to ppm at other temperatures and pressures, one must calculate the volume of 1 gram molecular weight of an airborne contaminant (e.g. 92.13 grams of toluene) by using the formula: V = (RT/ P) where R is the ideal gas constant; T, the temperature in kelvins (273.16 + T°C); and P, the pressure in mm Hg. This information can be substituted in the formulas for converting between mg/m3 and ppm. TLV in mg/m3 = (P/RT) x MW x (TLV in ppm) = P x MW x (TLV in ppm) 62.4 x (273.2 + T°C) and TLV in ppm = 62
