Chapter 22, Problem 85IAE

Interpretation Introduction

Interpretation:

The concentration of ${\text{NO3}}^{\text{-}}$ on the basis given reaction and information about qualitative analysis of ammonia gas released should be determined.

Concept introduction:

The reaction of nitrate ion in basic medium with zinc metal reduces ${\text{[NO3]}}^{\text{-}}$ ions to ammonia gas. For the determination of concentration of ${\text{[NO3]}}^{\text{-}}$ ions, the released ammonia can be titrated with excess of HCl as it forms ammonium chloride as the acid-base reaction.

$\text{NH3+HCl }\to \text{ NH4Cl}$

The excess of HCl can be determined with the help of NaOH. Hence moles of NaOH used give the concentration of HCl and moles of HCl gives information about the ammonia released.