Chapter 19, Problem 27E

Interpretation Introduction

Interpretation : The properties of oxalic acid making it useful to remove the rust stain needs to be explained.

Concept Introduction : The formula of the rust is ${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}$ . It is formed by oxidation of iron when it comes in contact with moisture in the air. Oxalic acid is an organic compound containing carboxylic acid group. It is used as a reducing agent; the chemical formula is ${\text{H}}_{\text{2}}{\text{C}}_{\text{2}}{\text{O}}_{\text{4}}$ thus, the formula of its conjugate base is ${\text{C}}_{\text{2}}{\text{O}}_{\text{4}}{}^{2-}$ .