Ozonolysis is a method used to locate the position of double bonds in alkenes.

1. Ozone Addition: $O_3$ adds across the double bond to form an unstable ozonide.
2. Reductive Cleavage: The ozonide is treated with $Zn$ and $H_{2}O$. The zinc prevents the formation of $H_2{O}_2$ (which would oxidize products to acids).

• The double bond is 'clipped' and replaced by oxygen atoms $(C=O)$.
• Result: Depending on the substitution, aldehydes or ketones are produced.