Q.How is ozone prepared in the laboratory using a Siemens ozoniser? Describe the structure of the ozone molecule.

[!TLDR] Ozone is made by passing dry O2 through a silent electric discharge (Siemens ozoniser); it is bent (sp2 central O, ~116.8 degrees), a resonance hybrid with equal O-O bond lengths. [!ANSWER] Ozone is prepared as $3\text{O}_2 \rightarrow 2\text{O}_3$ via a s …

Ozone is prepared in the laboratory using a Siemens ozoniser: dry oxygen gas is passed between two coaxial electrodes separated by a narrow gap, across which a high-voltage silent (non-sparking) electric discharge is maintained, converting a small fraction of the oxygen to ozone: $3\text{O}_2 \xrightarrow{\text{silent electric discharge}} 2\text{O}_3$ A silent discharge (rather than an ordinary hot spark) is essential because ozone is thermodynamically unstable relative to $\text{O}_2$ and decomposes readily if heated. Structurally, ozone is a bent (angular) molecule: the central oxygen atom is $sp^2$ hybridised with one lone pair, giving an O-O-O bond angle of about $116.8^\circ$. Although a simple valence-bond picture would suggest one O=O double bond and one O-O single bond, the two bonds are found experimentally to be of equal length (about 128 pm, intermediate between a typical single and double O-O bond) -- explained by resonance between two equally-valid ca …

State the ozoniser preparation with its balanced equation, then describe the bent shape and explain the equal bond length …

Using an ordinary spark instead of a silent discharge in the description (a spark decomposes ozone rather than forming it …