A STUDY OF NITRIC OXIDE-CONCENTRATED SULFURIC ACID REACTION

The reaction between nitric oxide and concentrated sulfuric acid (96 wt. per cent) was studied at 25° with the aid of chronopotentiometry and mass spectrometry. The amounts of products found indicate that the reactions involved in this system are (1) 4NO + 3H2SO4 → 2NO+ + N2O + H3O+ + 3HSO4- and (2) 2NO + 5H2SO2 → 2NO+ + SO2 + 2H3O+ + 4HSO4- with the first reaction being more important initially but the second occurring to a larger extent at longer times. Neither reaction was found to have reached equilibrium even after runs of long duration. Thermodynamic calculations yield 2 × 1050 (mole/l)3 and 4 × 1012 (mole/l)7 for the equilibrium constants of reactions (1) and (2), respectively. The rate of reaction was found to depend on the gas-liquid interfacial area, but by eliminating the gas phase one could observe the kinetics for the first few hours to be second order in nitric oxide for reaction (2). The rate constant for reaction (2) was measured as 0·20±0·04 l./mole sec. © 1968.