Nitric acid can be made in a 3-stage process. Stage 1 Stage 2 Stage 3
Ammonia is oxidised by oxygen from the air, to form nitrogen monoxide and water. This reaction is carried out at 10–13 atmospheres pressure and 900 °C in the presence of a platinum catalyst.
Nitrogen monoxide reacts with more oxygen to form nitrogen dioxide. 2NO + O2 2NO2 ∆H = –114kJmol–1
Nitrogen dioxide reacts with water to make nitric acid and nitrogen monoxide. 3NO2 + H2O → 2HNO3 + NO
(a) Write an equation to show the reaction occurring in stage 1. [1]
(b) Draw a ‘dot-and-cross’ diagram to show the arrangement of outer electrons in a molecule of ammonia. Llr