Condensation reactions.  
A condensation reaction, is one where two molecules join together to form one larger molecule with the expulsion of a small molecule, usually water. Atlhough water is the small molecule produced during condensation reaction in organisms this is not always the case in industry, wehere acetic acid or hydrochloric acid are among the molecules that can be produced.

A condesation reaction occurs when two functional groups react. Below are some examples.

Functional groups involved Small molecule ejected Type of bond formed.
Carboxyl and hydroxyl

Carboxyl and amine


Two hydroxyl groups


1) One ethanoic acid molecule and one molecule of ethanol react in a condensation reaction to form a bigger molecule.
a) What is the molar mass of this molecule?

b) Draw the strucutral formula of this molecule.

c) What type of functional group is formed as a result of this reaction?

d) Draw the structural formula of the molecule.


2) Glycine and alanine are two amino acids pictured on the right.

a) Draw the structural formula of the molecule that results when the two amino acids react.

b) What type of functional group is formed?

c) Why is this reaction considered a condensation reaction?

Continue with some biological condensation reactions