Railway Science (Chemistry-Chemical Reaction)

When Chlorine (Cl) is passed over dry slaked lime (Ca(OH)₂) at room temperature, the main reaction product is Ca(OCl)2 (bleaching powder). Reaction: (Ca(OH)₂) (aq) + Cl₂(g) CaOCl₂ → (aq) + H₂O.

AgNO₃ (Silver Nitrate) + NaCl (sodium chloride) → AgCl (silver chloride) + NaNO₃ (silver nitrate) an example of a Double Displacement Reaction (a reaction in which the positive and negative ions compounds exchange took place to form two new compounds).
Redox Reaction - A reaction in which oxidation and reduction take place simultaneously. Examples: ZnO (Zinc Oxide) + C (Carbon) → Zn (Zinc) + CO (Carbon Monoxide), MnO₂ (Magnesium Oxide)+ 4HCl (Hydrochloric acid) → MnCl₂ (Magnesium Chloride) + 2H₂O (water) + Cl₂ (Chlorine), 4Na (Sodium) + O2 (Oxygen) → 2Na₂O (Sodium Oxide).

Precipitation reaction: a chemical reaction occurring in an aqueous solution where two ionic bonds combine, resulting in the formation of an insoluble salt. These insoluble salts formed in precipitation reactions are called precipitates. Examples - AgNO₃ (Silver Nitrate)(aqueous) + KCl (Potassium Chloride) (aqueous) → AgCl (Silver Chloride)(precipitate) + KNO₃ (Potassium Nitrate)(aqueous), These are used for the extraction of magnesium from the seawater and also in wastewater treatment.

Balanced Chemical reaction - If there are no inequalities in the number of atoms, between Reactant side and product side. BaCl₂ ( Barium Chloride )is used in the purification of the brine solutions that are used in caustic Chlorine plants. Al₂(SO₄)₃ (Aluminium Sulphate) is soluble in water and used in the purification of drinking water and wastewater treatment plants as a coagulating agent as well as in paper processing.

Chemical reactions need to be balanced to abide by the law of conservation of mass which states that matter cannot be created or destroyed (or to make the number of the atoms of the reactants equal to the number of the atoms of the products).

AgN𝑂₃ + KBr → AgBr + KN𝑂₃ Silver Bromide (AgBr) is used in 3 photographic film. Potassium Nitrate (KN𝑂₃) is used as food preservatives,  fertilizers, tree stump removal, rocket propellants, and fireworks. Silver Nitrate (AgN𝑂₃ ) is known for its antibacterial properties and is used as a disinfectant, antiseptic and antimicrobial agent. Potassium Bromide (KBr) is a halide anticonvulsant used in veterinary medicine for the treatment of epilepsy.

Hydrogen and Oxygen are combined to form a single product.
2𝐻₂(g) + 𝑂₂(g) → 2𝐻₂O(l).

Examples: combination reaction - 2H₂ + O₂→ 2H₂O.
PQ + R → PR + Q : Displacement Reaction - 2Na + 2HCl → 2NaCl + H₂.
XY→ X +Y : Decomposition Reaction - 2HgO → 2Hg +O₂ .
AB + CD → AC + BD : Double Displacement Reaction- AgNO₃ + HCl → AgCl + HNO₃

The chlor alkali process produces sodium hydroxide, including chlorine and hydrogen. This is done by electrolysis of a sodium chloride solution. It is also called electrolysis of brine. Sodium hydroxide is used to produce soaps, rayon, paper, products that explode, dyes, and petroleum products. Hydrogen can be used to power vehicles, generate electricity, power the industry, and heat our homes and businesses.

After burning magnesium ribbon, it changes into a white powder (MgO). Magnesium ( Mg) + Oxygen (Reactant) → Magnesium Oxide (MgO).
2Mg + O₂→ 2MgO. Magnesium oxide can be used as an antacid to relieve heartburn, sour stomach, or acid indigestion.