Railway Science (Chemistry-Chemistry in Everyday life)

When a cold and concentrated solution of sodium chloride (NaCl) reacts with ammonia (NH₃) and Carbon dioxide (CO₂), Sodium hydrogen carbonate (NaHCO₃) and ammonium chloride (NH₄Cl) are formed. Reaction - NaCl + NH₃ + H₂O + CO₂ → NaHCO₃ (baking soda) + NH₄Cl.

Ca(OH)₂ (Calcium Hydroxide or Slaked lime) + CO₂ (Carbon dioxide) → CaCO₃ (Calcium carbonate) + H₂O (water). Calcium carbonate is also the chemical formula of Chalk or marble.
Calcium hydroxide [Ca(OH)2 ] is obtained by reaction of water and calcium oxide. CaO (Calcium oxide) + H₂O (water) → Ca(OH)₂ (slaked lime). Uses of Ca(OH)₂ - in whitewashing the walls, in sewage treatment, in the paper industry.

Washing Soda (Na₂CO₃.10H₂O): Chemical Name - Sodium carbonate decahydrate. Properties - Grayish white powder, odourless, Alkaline taste, stable at ordinary temperature, water soluble. It is made by the Solvay Process. Uses: Soap, paper and glass industries , remove permanent hardness of water.

Recrystallisation of Na₂CO₃ (sodium carbonate) gives Washing soda. Na₂CO₃ (Sodium Carbonate) + 10H₂O → Na₂CO₃.10H₂O (Washing Soda). It means that when sodium carbonate is produced, water is added to it again to purify it and it is allowed to crystallise again, then it forms washing soda. It is used in glass, soap, and paper industries. It is also used in removing the permanent hardness of the water.

Ozone (O₃) is a highly reactive gas composed of three oxygen atoms. It is found in the stratosphere of the atmosphere. Chlorofluorocarbon (CFC) is responsible for its depletion.
The first ozone hole was discovered in 1970 in the stratosphere over Antarctica. Montreal Protocol (1987) is a global agreement to protect the stratospheric ozone layer. Dobson (Measuring unit ).

Refrigerants. CFC - Chlorofluorocarbon (man- made fluorinated gas) is an organic compound that does not occur naturally. It contains carbon, chlorine, and fluorine, produced as a volatile derivative of methane, ethane, and propane.
It is used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents. CFCs are a group of odorless manufactured chemicals. Chlorofluorocarbons cause depletion of the Ozone (O₃) layer in the stratosphere.

Methane (CH₄) is one of the three main greenhouse gases, along with carbon dioxide (CO₂) and nitrous oxide (N₂O). Biogas is produced by using organic material, which is broken down with the help of bacteria in an anaerobic environment in the absence of oxygen. Raw biogas typically consists of methane (50–75%), carbon dioxide (25–50%), and smaller amounts of nitrogen (2–8%).

Helium (He), chemical element, inert gas of Group 18 of the periodic table. The second lightest element (after hydrogen). Helium is a colorless, odorless, and tasteless gas that becomes liquid at −268.9 °C (−452 °F).
Application: Used for medicine, scientific research, arc welding, refrigeration, gas for aircraft, coolant for nuclear reactors, cryogenic research and detecting gas leaks.

Alum (aluminium sulfate) is a hydrated double salts. Different types of alum - Potash Alum {KAl (SO₄)₂ .12H₂O}, Sodium Alum {NaAl (SO₄ .12H₂O}, Ammonium Alum {NH₃Al (SO₄ .12H₂O}.Reverse osmosis (RO) is a water purification process.
Nitrogen - It is used to make fertilizers, nitric acid, nylon, dyes and explosives. Sodium is used as a heat exchanger in some nuclear reactors, and as a reagent in the chemicals industry.

Polyvinyl Chloride (PVC) - It is a high-strength thermoplastic material and used for the manufacturing of water pipes, Raincoats, Handbags etc. Polystyrene used - Food packaging, CD and DVD cases, Building and construction, etc. Bakelite - Sockets, wire insulation, switches and automobile distribution caps etc. Glyptal - Paints, coating metals, and lacquers.