Question

Give reasons for:
'' Carbon-oxygen bond lengths in formic acid are $1.23\mathring{A}$ and $1.36\mathring{A}$ and both the carbon-oxygen bonds in sodium formate have the same value .i.e. $1.27\mathring{A}$''

Answer 1

Both formic acid and sodium formate exhibit the phenomenon of resonance as :

In formic acid, the extent of delocalisation is less compared to sodium formate because of charge separation in the former case. Due to this reason, the bond length between carbon and $s{p}^3$ oxygen in formic acid is slightly greater than the same between carbon and $s{p}^2$ oxygen. In formate ion, there is no separation of charge and both the resonance structures are equivalent giving equal bond length of both carbon oxygen bonds.