. "mole concentration of ethene in air" . "Climate and Forecast (CF)" . . . " Mole concentration means number of moles per unit volume, also called \"molarity\", and is used in the construction mole_concentration_of_X_in_Y, where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as 'nitrogen' or a phrase such as 'nox_expressed_as_nitrogen'. The chemical formula for ethene is C2H4. Ethene is a member of the group of hydrocarbons known as alkenes.There are standard names for the alkene group as well as for some of the individual species." .