Question

What is the composition of Devarda’s alloy? Which gas evolves when this alloy is treated with $HN{O}_3$?

Answer 1

Hint: Alloys are metal mixtures with additional elements whose precise composition is determined by the qualities required. Because alloys are metallic in nature, they have excellent thermal and electrical conductivity.

Complete answer:
Devarda’s alloy is an alloy which consists of aluminium ($44\mathrm{\%}-46\mathrm{\%}$), Copper ($49\mathrm{\%}-51\mathrm{\%}$) and Zinc ($4\mathrm{\%}-6\mathrm{\%}$).
When Devarda’s alloy is treated with $HN{O}_3$, ammonia gas is evolved.
In analytical chemistry, Devarda's Alloy is used as a reducing agent to determine nitrates after they have been reduced to ammonia under alkaline circumstances. Prior to the introduction of ion chromatography, it was also utilised in the quantitative or qualitative analysis of nitrates in agriculture and soil research. It's a crucial raw ingredient and intermediary in organic and medicinal chemistry.
Devarda's alloy is a silvery-gray metallic alloy with no odour and no liquid solubility. It melts at $490$ to $560$ degrees Celsius and boils at $906$ degrees Celsius. It has a bulk density of $2.08g/c{m}^3$ and a density of $5.79g/c{m}^3$ at ${20}^{\circ }C$.
Devarda's alloy releases hydrogen when it reacts with bases like sodium hydroxide. Aluminium, copper, and zinc are melted together to produce Devarda's alloy. Devarda's alloy is toxic if consumed or inhaled.

Note:
Devarda's alloy, when powdered, is combustible and should be handled with caution. Devarda's alloy should be kept away from bases, acids, and oxidizers in sealed bottles. By neutralising Devarda's alloy with an acid and then reducing it, copper and zinc can be recovered. It can also be thrown away.