Separate chemistry 1 Study Guide

Rusting is the corrosion of iron and its alloys, a redox process where iron reacts with oxygen and water to form hydrated iron(III) oxide. Prevention methods focus on creating barriers or altering the electrochemical conditions. Excluding oxygen involves coating the iron with materials like paint, oil, or plastic, preventing atmospheric oxygen from reaching the metal surface. Similarly, excluding water, a key reactant, can be achieved by applying waterproof layers or storing iron in dry conditions. Sacrificial protection uses a more reactive metal (e.g., zinc or magnesium) in electrical contact with iron. This more reactive metal oxidises preferentially, corroding instead of the iron, thereby 'sacrificing' itself and leaving the iron intact.

Ammonia (NH₃) is a weak base, and nitric acid (HNO₃) is a strong acid. When these two substances react, they undergo a neutralisation reaction. In this specific case, the reaction produces ammonium nitrate (NH₄NO₃). This salt is highly soluble in water and is a very effective fertiliser because it contains two essential plant nutrients: nitrogen from both the ammonium ion (NH₄⁺) and the nitrate ion (NO₃⁻). The overall chemical equation for this reaction is: NH₃(aq) + HNO₃(aq) → NH₄NO₃(aq). Because both reactants are typically used in aqueous solutions, the product, ammonium nitrate, is also formed in solution. The process involves carefully mixing the two reactants, often under controlled conditions to manage the heat released, as neutralisation reactions are exothermic. The resulting solution can then be concentrated and crystallised to obtain the solid fertiliser.