[stevieG22]

Q] The sodium salt of a carboxylic acid, A, was produced by passing gas ,B, into an aqueous solution of caustic alkali at an elevated temperature and pressure. A, on heating in presence of NaOH followed by treatment wih sulphuric acid gives oxalic acid  . Find A and B  and write the reactions involved .

: Well te answer given is that B is CO₂, A is HCOONa. But i dont get it how can formic acid be formed from NaOH and CO₂ because in CO₂ carbon is in +4 oxidation state while in formic acid it is in +2 state !! If carbon was reduced then who got oxidised ? 

[majorjp]

Are you sure that gas B is CO₂? Because sodium formate can be formed through a reaction of CO and NaOH to yield the Sodium Formate salt (NaHCO₂).

In this case the CO carbon is in the +2 oxidation state, and in the formic acid it retains that oxidation state