The -COONa group can be replaced by H atom in reaction with soda lime.
Soda lime is a mixture of NaOH and CaO.
RCOONa+NaOHCaO−−→RH+Na2CO3.
It is a decarboxylation reaction. CO2 is removed in the form of carbonate.
Alkane formed contains 1 carbon atom less than the carboxylic acid.