This is the 7233rd most frequent German word.
gases
"Gases" in German means "streets" or "alleys" (plural of "Gasse").
Here, 'Gasen' is the plural form of the noun 'Gas' in the dative case, part of a prepositional phrase indicating composition.
Die Luft in der Atmosphäre besteht aus verschiedenen Gasen.
The air in the atmosphere consists of various gases.
'Gase' is used as the plural form of the noun 'Gas' as the subject in a situation implying release or escape.
Durch das Leck im Rohr entweichen gefährliche Gase.
Dangerous gases escape through the leak in the pipe.
Similarly, 'Gasen' appears in the dative plural, specifying the entities involved in chemical reactions.