Q. What is the Ratio of Aqua Regia in NCERT

Aqua regia is prepared by mixing concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO₃) in a ratio of 3:1 by volume, meaning three parts HCl to one part HNO₃. This specific ratio creates a powerful oxidizing mixture capable of dissolving noble metals like gold and platinum that resist attack by individual acids. The name "aqua regia" translates from Latin as "royal water," reflecting its ability to dissolve gold, the "king of metals." This mixture appears in NCERT Class 10 chemistry when discussing how even highly unreactive metals can be dissolved under specific chemical conditions.

The exceptional dissolving power of aqua regia results from the chemical reactions between the two acids, which generate nascent chlorine and other reactive species that can oxidize even gold and platinum. The 3:1 ratio is optimal because it provides the right balance of oxidizing agents and complexing agents needed to both oxidize the metal and stabilize the resulting metal ions in solution. When preparing aqua regia in laboratory settings (though Class 10 students typically only learn about it theoretically), concentrated acids must be mixed carefully with proper safety precautions as the reaction is highly exothermic and produces toxic fumes. This mixture demonstrates important principles: that chemical behavior depends on combinations of substances not just individual properties, that even "inert" materials have specific conditions under which they react, and that understanding acid chemistry has practical applications in metallurgy, jewelry processing, and analytical chemistry.