Polymerized formaldehyde is known as which compound?

• A. Paraformaldehyde
• B. Formalin
• C. Formaldehyde polymer
• D. Methoxymethyl aldehyde

Answer: (A)

Formaldehyde can link into long chains, forming a solid polymer called paraformaldehyde. This polymer looks like a white powder and, when heated or dissolved in water, it depolymerizes back into formaldehyde monomer. That’s why paraformaldehyde is described as the polymerized form of formaldehyde. In the lab, formalin refers to the aqueous, stabilized solution of formaldehyde used for routine fixation, whereas paraformaldehyde is the solid form used in other fixation protocols or when making formaldehyde solutions. Other terms like “formaldehyde polymer” describe the concept in general, but the standard name for the polymer is paraformaldehyde, and methoxymethyl aldehyde is a different compound altogether.