ABSTRACT
The flow rate of a monomer is generally given by the volume of the gas at standard temperature and pressure (273K and 1 atm) per unit time (e.g., cm3STP/min, which is often designated as standard cubic centimeters per minute, ‘‘sccm’’). In the gas phase, the pressure and volume determine the total number of molecules of the gas under consideration. In other words, in order to define a system one must define pV; p or V alone cannot define the system. In contrast to this situation for a gas, with a noncompressible liquid the volume alone can be used to define the system. Thus, 1 cm3STP, means 1 cubic centimeter at 1 atm and 273K, the dimension of which is not L3 but L3p. Therefore, the flow rate given by cubic centimeters (STP) per minute, sccm, is proportional to moles per minute. Thus, it is important to recognize that cubic centimeters (STP) does not represent the volume of a gas but gives a value proportional to the number of moles of a gas.
