DETERMINATION OF NITRIC-ACID CONCENTRATION IN THE HNO3-N2O4-H2O SYSTEM

The article discusses a procedure for quantitative water determination in mixtures containing greater than 20 wt. % of nitrogen tetroxide, which would allow calculation of nitric acid concentration. The proposed method allows analysis of acid concentration in the range 80-100 wt. % at a nitrogen tetroxide content up to the formation of layered mixtures. However, analysis of solutions containing more than 25-30 wt. % of nitrogen tetroxide needs high-pressure cuvettes. One determination involving two parallel experiments, including filling of the cuvette, takes 3-6 min.