What is a condensation reaction?

• A. H2O leaves, covalent bond forms
• B. H2O leaves, ionic bond forms
• C. H2O added, covalent bond forms
• D. H2O added, ionic bond forms

Answer: (A)

Condensation reactions, or dehydration synthesis, link two molecules by removing a water molecule. The missing water allows the atoms to share electrons and form a covalent bond, creating a larger molecule. This is why the best description is water leaving and a covalent bond forming. In biology you see this when amino acids form peptide bonds, sugars form glycosidic bonds, or fatty acids form ester bonds, each releasing water. If water were added, you’d be describing hydrolysis, which breaks bonds rather than forming them, and ionic bonds aren’t the typical product of these linking steps.