Illustration of resonance stabilisation of the p-nitrophenoxide anion, which leads to a lower pKa of p-nitrophenol compared to phenol. pKa values taken from <a href="//commons.wikimedia.org/wiki/File:Phenol_versus_nitro-phenol.jpg" title="File:Phenol versus nitro-phenol.jpg">File:Phenol_versus_nitro-phenol.jpg</a> by <a href="//commons.wikimedia.org/w/index.php?title=User:RLM0518&amp;action=edit&amp;redlink=1" class="new" title="User:RLM0518 (page does not exist)">User:RLM0518</a>.
<a href="//commons.wikimedia.org/wiki/User:Hbf878" title="User:Hbf878">Hbf878</a>
<span class="int-own-work" lang="en">Own work</span>