Introduction

A thorough discussion of chloramines, their uses, advantages, and problems, is presented in Section 10.1 of the companion book. Hypochlorous acid can react stepwise with ammonia so as to produce the three chloramines (i.e., mono-, di- and trichlo-ramine):

NH3(g) + HCIO -> NH2C1 + H20(d (1) NH2C1 + HCIO NHC12 + H20(I) (2) NHC12 + HCIO NC13 + H20(d (3)

The predominance diagram as a function of pH for the three chloramines is given in Figure 1, and their species distribution diagram is given in Figure 2.

Chloramine Analysis

Chloramines can be analyzed by titrimetry, colori-metry (with /V./V-diethyl-p-phenylenediamine, DPD), voltammetry, UV spectrophotometry, am-

perometry, mass spectrometry, HPLC, and other methods.

In the present experiment students will produce the three chloramines and characterize them qualitatively by UV spectroscopy, taking advantage of the simplicity of this analytical method.

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