Class 10 Science - ICSE-CHEMISTRY
Study of Compounds – Ammonia
The chapter 'Study of Compounds – Ammonia' in Class 10 ICSE Chemistry explores the preparation, properties, and uses of ammonia, an industrially vital nitrogen compound. Students learn the laboratory preparation of ammonia gas from ammonium salts and its manufacture on a large scale via Haber's Process. Key chemical properties covered include its basic nature, reducing property, and the characteristic aqueous reactions with metal ions like copper and iron. A major focus is placed on the Fountain Experiment, which demonstrates its extreme solubility in water. Mastery of this chapter is essential for scoring well in ICSE Board chemistry exams, particularly in chemical equations and observation-based questions.
Start Learning FreeKey Concepts
Laboratory Preparation
Ammonia is prepared in the lab by heating an ammonium salt, such as ammonium chloride, with a non-volatile alkali like calcium hydroxide, followed by drying over quicklime.
Haber's Process
Industrial manufacture of ammonia combines nitrogen from fractional distillation of liquid air and hydrogen from water gas, reacting them at high pressure and temperature in the presence of an iron catalyst and molybdenum promoter.
Fountain Experiment
This classic demonstration proves that ammonia is extremely soluble in water and possesses an alkaline nature, creating a dramatic colored fountain inside a round-bottom flask.
Action with Metal Ions (Precipitation Reactions)
Aqueous ammonia reacts with metallic salt solutions like copper sulfate, ferrous sulfate, and zinc chloride to form characteristic colored metal hydroxide precipitates.
Catalytic Oxidation of Ammonia
When ammonia is heated with excess oxygen in the presence of platinum gauze at 800°C, it oxidizes to nitric oxide and water, which is the first step in the Ostwald process for nitric acid.
Important Formulas
Board Exam Info
In the ICSE Chemistry (Science Paper 2) exam, this chapter typically contributes about 4 to 6 marks. Questions frequently appear as balanced chemical equations, identifying gases based on observations (such as turning moist red litmus blue or forming dense white fumes with HCl), and explaining specific industrial conditions or apparatus setups like the drying agent used.
Frequently Asked Questions
Why is concentrated sulfuric acid not used to dry ammonia gas?
Concentrated sulfuric acid is a drying agent, but it is acidic and reacts chemically with basic ammonia gas to form ammonium sulfate, rather than just drying it.
How is ammonia gas collected in the laboratory and why?
Ammonia is collected by the downward displacement of air because it is much lighter than air (vapor density is 8.5) and highly soluble in water, making water displacement impossible.
What happens when excess ammonia is added to copper(II) sulfate solution?
Initially, a pale blue precipitate of copper(II) hydroxide forms, which dissolves in excess ammonia to give a deep inky-blue solution of tetramminecopper(II) sulfate.
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