Unit 13: Chemical Industry

13.1 hand-out

13.2 Fertilizers

Plants! Plants don’t only need CO2, light, & H2O They need Nitrogen to make amino acids & proteins Can’t really get it from the air (can’t utilize N2) Get it from the soil as nitrates or ammonium salts Farmed crops remove N from the soil Phosphorus & Potassium too Must be replaced

Fertilizers Fertilizer: substance added to the soil to replace the elements taken up by plants. Also increases the crop yields Animal Manure – natural fertilizer Artificial Fertilizer: Replace lost nitrogen, phosphorus, and potassium NPK Fertilizers

Fertilizers Compound Fertilizer: may contain ammonium nitrate, ammonium phosphate, and potassium chloride Single Fertilizer: Only ammonium nitrate

Making Fertilizers ~10% of the chemical industry is involved in making fertilizers. Haber Process: chemical reactions that yield ammonia Contact Process: chemical reactions that yield sulfuric acid Potassium comes from salts that are mined

Displacement of Ammonia Fertilizers are slightly acidic Farmers add lime to the soil Lime reacts with water to form slaked lime, Calcium Hydroxide (alkaline). If too much lime is put in the soil, it reacts with the ammonium salts in fertilizers to release ammonia (not good).

Displacement of Ammonia Ammonium + Calcium  Ammonia + Calcium + water Chloride Hydroxide Chloride 2NH4Cl(aq) + Ca(OH)2  2NH3(g) + CaCl2(aq) + H20(l)

13.3 Limestone Industry

Limestone Main source of limestone is calcium carbonate A rock Formed millions of years ago from the remains of sea creatures

Lime Thermal Decomposition: compounds break down when heated, forming two or more products from one reactant Heated limestone breaks down into calcium oxide (lime) and carbon dioxide calcium carbonate → calcium oxide + carbon dioxide CaCO3 → CaO + CO2

Making Lime Lime is made by heating limestone in a rotary kiln.

Slaked Lime Slaked Lime: name for Calcium Hydroxide Made from lime by adding water slowly. Calcium Oxide + Water  Calcium Hydroxide Solution of slacked lime is called limewater 

Uses of Limestone Products Limestone Uses: Building Extraction of Iron Construction of Roads Manufacture of Cement

Uses of Lime Lime & Slacked Lime Uses: Treatment of excess acidity in soils & Lakes Neutralizing acidic industrial waste products, e.g. flue gas desulfurization. Removes sulfur dioxide from burning coal.