Question

In a Bronsted acid-base reaction, the stronger acid reacts with the stronger base to produce a weaker acid and a weaker base. Thus, whether a reaction “goes” or “does not go” can be used to determine the relative strength of the Bronsted acids and bases in the reaction. From the data below, determine the order of the strengths of the three Bronsted acids.
Reaction 1: CH3CO2H + H2AsO3- → H3AsO3 + CH3CO2- goes Reaction 2: H2AsO4- + H2AsO3- → H3AsO3 + HAsO42- goes Reaction 3: CH3CO2H + HAsO42- → H2AsO4- + CH3CO2- goes

Answer 1

Since CH3CO2H react with both HAsO42- and H2AsO3- and release H+ ion thus it is strongest Bronsted acid.

Since H2AsO4- react with H2AsO3- and release H+ ion thus H2AsO4- is stronger acid than H3AsO3.

Hence, order is :

H3AsO3 < H2AsO4- < CH3COOH