Acidimetric determination of NH4 or NH3 after distillation

2 Acidimetric determination of NH4+ or NH3 after distillation General remarks 

Ammonium ions and dissolved ammonia are distilled off with water vapour as NH3 at pH 7.4 and collected in a receiver containing boric acid. The primary ammonium salt of boric acid thus formed undergoes hydrolysis until equilibrium is established according to 

It is also possible to collect the NH3 in a known quantity of sulphuric 

Laboratory air etc., chemicals and the water used to produce the water 

In order to remove free chlorine, add 1 ml of sodium thiosulphate solution per mg of chlorine before distillation. 

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