Formaldehyde is an organic compound with the chemical formula CH2O and a relative molecular weight of 30.03. Colorless gas with a strong irritating and suffocating odor, especially irritating to the eyes and mucous membranes of humans. It can dissolve in water and form an aqueous solution of formaldehyde. Melting point -92 ℃, boiling point -21 ℃. Relative density 0.815g/cm ³.