Class 10 Science - ICSE-CHEMISTRY
Study of Compounds – Nitric Acid
The chapter 'Study of Compounds – Nitric Acid' in ICSE Class 10 Chemistry explores the preparation, properties, and uses of one of the most important mineral acids. Students learn the laboratory preparation of nitric acid using concentrated sulphuric acid and potassium nitrate, and its industrial production via the Ostwald's process. The chapter highlights the unique oxidizing and thermal decomposition properties of nitric acid, including its reaction with metals and non-metals. Mastery of this chapter is vital for board exams as it heavily features chemical equations, observation-based questions, and reasoning problems about why concentrated nitric acid behaves differently from other acids.
Start Learning FreeKey Concepts
Laboratory Preparation
Nitric acid is prepared in the lab by heating potassium nitrate or sodium nitrate with concentrated sulphuric acid in an all-glass apparatus at a temperature below 200°C.
Ostwald's Process
Industrial manufacturing of nitric acid involves the catalytic oxidation of ammonia by atmospheric oxygen in the presence of platinum at 800°C, followed by absorption of nitrogen dioxide in water.
Unstable Nature
Pure nitric acid is a colorless liquid, but it turns yellow upon standing due to the accumulation of dissolved nitrogen dioxide gas produced by its thermal decomposition in sunlight.
Strong Oxidizing Agent
Nitric acid acts as a powerful oxidizing agent because it thermally decomposes to release nascent oxygen, which readily oxidizes both metals and non-metals.
Action with Metals
Unlike other acids, nitric acid generally does not liberate hydrogen gas with metals because the hydrogen produced is oxidized to water by the acid itself.
Aqua Regia
A freshly prepared mixture of one part concentrated nitric acid and three parts concentrated hydrochloric acid by volume, capable of dissolving noble metals like gold and platinum.
Important Formulas
Board Exam Info
In the ICSE Chemistry (Science Paper 2) board exam, this chapter typically carries around 4 to 6 marks. Questions frequently appear as chemical equations for preparation, balanced equations for oxidizing properties, observations of color changes, and reasoning questions such as why an all-glass apparatus is used in the laboratory preparation.
Frequently Asked Questions
Why is an all-glass apparatus used in the laboratory preparation of nitric acid?
Glass is used because nitric acid vapor is highly corrosive and would attack and corrode cork or rubber stoppers if used in the setup.
Why does concentrated nitric acid turn yellow on standing?
It turns yellow because the acid undergoes slow thermal decomposition in the presence of sunlight, releasing nitrogen dioxide gas which dissolves back into the acid.
Why does nitric acid not typically liberate hydrogen gas when reacting with metals?
Nitric acid is a strong oxidizing agent. Any hydrogen gas produced during the reaction is immediately oxidized by the acid to form water.
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