Question

What is: [3 MARKS]
(a) aqua fortis
(b) aqua-regia
(c) fixation of nitrogen?

Answer 1

Each Part: 1 Mark

(a) Aqua fortis : Nitric acid was formerly known as aqua fortis, which means strong water.

(b) Aqua-regia : A mixture of conc. nitric acid (1 part by volume) and conc. hydrochloric acid (3 parts by volume) is called aqua-regia. Aqua-regia means royal water. It reacts even with gold and platinum to give their chlorides. Aqua regia contains nascent chlorine which attacks these metals.
$HN{O}_3+3HCl\to \underset{Nitrosylchloride}{NOCl}+2H_{2}O+\underset{Nascentchlorine}{2\left[Cl\right]}\underset{Platinum}{Pt}+4\left[Cl\right]\to \underset{Plainum\left(IV\right)chloride}{PtC{l}_4\left(soluble\right)}\underset{Gold}{Au}+3\left[Cl\right]\to \underset{Gold\left(III\right)chloride}{AuC{I}_3\left(soluble\right)}$

(c) Fixation of nitrogen: The conversion of free atmospheric nitrogen into useful nitrogenous compounds in the soil, is called "fixation of nitrogen."