Chapter 22, Problem 22.164MP

Interpretation Introduction

(a)

Interpretation:

The plausible structures for ${\text{H}}_{\text{3}}{\text{PO}}_{\text{3}}$ and the shape of the $\text{pH}$ titration curve for the titration of ${\text{H}}_{\text{3}}{\text{PO}}_{\text{3}}$ with aqueous $\text{NaOH}$ needs to be determined.

Concept introduction:

The main group elements tend to form oxyacid which are usually polyprotic acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}{\text{, H}}_{\text{3}}{\text{PO}}_{\text{4}}{\text{, H}}_{\text{3}}{\text{PO}}_{\text{3}}$ etc. The concentration and pH of polyprotic acid can be determined with the help of acid-base titration. The concentration of acid and base used for titration are used to determine the pH of solution with the help of titration curve.

Interpretation Introduction

(b)

Interpretation:

The pH at the first and second equivalence points needs to be determined assuming30.00 mL of 0.1240 M ${\text{H}}_{\text{3}}{\text{PO}}_{\text{3}}$ is titrated with 0.1000 M NaOH. Ka₁ = 1.0 x 10-2 Ka₂ = 2.6 x 10-7

Concept introduction:

The main group elements tend to form oxy-acids which are usually polyprotic acids like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}{\text{, H}}_{\text{3}}{\text{PO}}_{\text{4}}{\text{, H}}_{\text{3}}{\text{PO}}_{\text{3}}$ etc. The concentration and pH of polyprotic acid can be determined with the help of acid-base titration. The concentration of acid and base used for titration are used to determine the pH of solution with the help of titration curve.