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