Another way of expressing this value is ppmv. These are identical for an ideal gas, and practically identical for most gases of air pollution interest at 1 atm. In air pollution literature ppm applied to a gas, always means parts per million by volume or by mole. Parts per Million by Volume (or mole) in Air Parts Per Million (ppm) in proportion of:Ĭopyright © 1998-2008 Lenntech Water Treatment & Air Purification Holding B.V. Use extra zero's to expand the significance. The significance is automatically determined. If the molecular weight is unknown to you, please try our Molecular Weight Calculator.īy entering either the concentration in units of or in units of, the value will be converted directly and displayed in the field at the bottom. In the input field of Molecular Weight you could either choose from the drop-down list, or you could fill in the value of the molecular weight of the gas. For more theory about the use of ppm, please see the documentation below. The use of ppm therefore has to be specified in the input fields below, in the way it should convert the value with the proper unit. The unit ppm is used in several branches in different ways. This converter calculates the measured value in units of into units of and visa versa. Parts Per Million (ppm) Converter for Gases Separation and Concentration Purification Request.Plant Inspection & Process Optimalisation.What is its volume at Standard Ambient Temperature and Pressure? What is its volume at Normal Temperature and Pressure? What is its volume under the new STP definition? * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * STP Calculationsġ) A gas has a volume of 13.2 liters under the conditions of the old definition of STP (273.15 K and a pressure of 760 torr). Under these criteria, the molar volume value is 24.789. With these criteria, the value of molar volume is 24.0458.Ĥ) For Standard Ambient Temperature & Pressure (SATP) the criteria are 298.15K and 750.06 Torr. The new value of molar volume is 22.7109 liters.ģ) The National Institute of Standards and Technology (NIST) uses a standard called " Normal Temperature and Pressure" (NTP) (293.15K and 760 Torr). SATP (Standard Ambient Temperarure & Pressure)ġ) The first IUPAC method listed (replaced in 1982) defined STP as 273.15 K and 760 Torr.Įven though this is an old system, this method is still being reported on many websites and a great many Internet calculators continue to use it.Īlso, some websites continue to state the old value of molar volume as 22.4139 liters withoutĢ) In 1982, the International Union of Pure and Applied Chemistry (IUPAC) changed the pressure criterion to 750.06 Torr but left the temeperature criterion unchanged. Yes, it's great having STP calculators, but sometimes you have to figure things out for yourself.īefore we do some calculations, let's first define the 4 systems for comparing gas volumes that are currently being used. STANDARD TEMPERATURE AND PRESSURE CALCULATIONSĬalculating Volume at Standard Temperature and Pressureįor an advanced STP calculator, click here
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