21. Nitric Acid: a. Ostwald Process:
Pt / Rh gauge 4NH 3 + 5O 2 → 4NO + 6H 2 O......( i) 500 K, 9bar
2NO + O2 YZZZZZZZX2NO2......( ii)
3NO2( g) + H2 O( l) → 2HNO3( aq) + NO( g)......( iii)
NO thus formed is recycled and the aqueous HNO3 can be concentrated by distillation upto ~ 68 % by mass. Further
concentration to 98 % can be achieved by dehydration with concentrated H2SO4.
Nitric acid is strong oxidizing agent in the concentrated as well as in the dilute state.
22. Phosphorus:
a. It shows the property of catenation to maximum extent due to most stable P – P bond.
b. It has many allotropes, the important ones are: i. White phosphorus ii. Red phosphorus iii. Black phosphorus