Abstract

Sulfur dioxide expenditure – X –, moles SO₂·mole⁻¹ HNO₃ –, required for reduction one mole of nitric acid at the process of product reflux by nitrogen isotopes separation by means of chemical exchange of nitrogen oxides and nitric acid was determined experimentally. Measurements were done in temperature range 283–380 K for 10.0±0.1 and 12.5 moles/l concentrations of nitric acid. For the 10 M HNO₃ X changes from 1.37 ± 0.09 at 283 ± 1 K to 0.39 ± 0.07 moles SO₂/mole HNO₃ at 380 ± 2 K. Equilibrium model of reduction of HNO₃ as well as method of calculation of X were proposed. Some data are given for the expenditure of SO₂ per one mole of nitric acid and one unit of product-nitrogen-15-, when temperature changes from 283 to 380 K and nitric acid concentration changes from 6 to 15 M.

Keywords:

• isotope separation
• isotopic exchange
• nitric acid, nitrogen 15
• nitrogen isotopes
• nitrogen oxides
• sulfur dioxide