Helium is the most used gas for pycnometry due to its ideal behavior; However, there are times where helium can be substituted for other gases. Helium has the ability to permeate into pores that are closed from the surface and interacts with some organic materials and microporous carbons. Nitrogen is the second most common gas, but also interacts with certain materials. Larger molecules such as sulfur hexafluoride and methane can be used to include the volume of very small pores in volume results from which density is being calculated.
Helium is the most used gas for pycnometry due to its ideal behavior; However, there are times where helium can be substituted for other gases. Helium has the ability to permeate into pores that are closed from the surface and interacts with some organic materials and microporous carbons. Nitrogen is the second most common gas, but also interacts with certain materials. Larger molecules such as sulfur hexafluoride and methane can be used to include the volume of very small pores in volume results from which density is being calculated.
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