‹ Chemistry simulationsChemistry · AS Level 9701 · 12 Nitrogen and sulfurFive simulations covering Topic 12: the shape and basicity of ammonia and the dative bond in the ammonium ion, ammonium salts as fertilisers and the problems they bring, nitrogen oxides from engines and the catalytic converter, sulfur dioxide and acid rain with flue gas desulfurisation, and the Contact process.
Ammonia is pyramidal because of its lone pair, and that same lone pair makes it a base: it accepts a proton to give the tetrahedral ammonium ion. Watch the proton arrive and the shape change.
Ammonia neutralises acids to give ammonium salts, the nitrogen fertilisers. But add an alkali to an ammonium salt and the ammonia comes straight back out, which is both the standard test for the ammonium ion and the reason fertiliser must not be spread with lime.
Inside a hot engine, nitrogen and oxygen from the air combine. The oxides that form damage health and make acid rain, so the exhaust passes through a catalytic converter where they are reduced back to nitrogen. Follow the gases through.
Burning fuel that contains sulfur puts sulfur dioxide into the air. It oxidises and dissolves to give sulfuric acid, which falls as acid rain. Flue gas desulfurisation removes it at the chimney using calcium oxide or calcium carbonate.
The same sulfur dioxide is a valuable raw material: oxidised over a vanadium(V) oxide catalyst it becomes sulfur trioxide and then sulfuric acid, the most produced industrial chemical in the world. The conditions are another Le Chatelier compromise.
Ammonia accepting a proton into the tetrahedral ammonium ion in 3D with its dative bond, ammonium salts as fertilisers and the problems they cause, nitrogen oxides formed in engines and removed by a catalytic converter, sulfur dioxide and acid rain with flue gas desulfurisation, and the Contact process for sulfuric acid.
Five simulations covering Topic 12: the shape and basicity of ammonia and the dative bond in the ammonium ion, ammonium salts as fertilisers and the problems they bring, nitrogen oxides from engines and the catalytic converter, sulfur dioxide and acid rain with flue gas desulfurisation, and the Contact process.
Nitrogen and sulfur is a free, browser-based simulation for Cambridge International AS & A Level Chemistry 9701 (topic 12 Nitrogen and sulfur). The same ideas are examined in Cambridge IGCSE Chemistry 0620 (topic 6 Chemical reactions, topic 10 Chemistry of the environment, topic 12 Experimental techniques and chemical analysis). The course is assessed in Paper 1 (Multiple Choice (AS)), Paper 2 (AS Structured), Paper 3 (Advanced Practical), Paper 4 (A Level Structured), Paper 5 (Planning, Analysis, Evaluation). Syllabus for examination in 2025-2027. There are 5 tabs, each a self-contained experiment with its own controls and live readings, and nothing to install: it runs on a laptop, tablet or classroom projector.
Full syllabus map: AS Level Chemistry 9701 topic 12.
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