Railway Science (Chemistry-Chemical Reaction) (Part-III)

Reduction is a method that effectively embroils electropositive elements or any electronegative element or the removal of oxygen or the addition of hydrogen. Examples - CO₂ (g) + H₂ (g) → CO (g) + H₂O (g), Zn + CuCl₂ (Cupric Chloride) → ZnCl₂ + Cu.
Decomposition - A chemical reaction in which one reactant breaks down into two or more products. Example - The decomposition of carbonic acid in soft drinks, H₂CO₃ → H₂O + CO₂ .
Oxidation - An atom or ion loses one or more electrons. Rusting is an oxidation reaction. The iron reacts with water and oxygen to form hydrated iron (III) oxide, which we see as rust.

A double-displacement reaction occurs when the positive and negative ions of two ionic compounds switch places to form two entirely new compounds in an aqueous solution.
Calcium - Atomic number (20), Atomic mass (40), Discovered by (Sir Humphry Davy). Sulfuric acid (𝐻₂S𝑂₄) is used to manufacture explosives, other acids, dyes, glue, wood preservatives, and automobile batteries.

Pb: Atomic number (82), Atomic mass (207.2). Properties - low melting point, ease of casting, high density, low strength, ease of fabrication, acid resistance. Uses - batteries, gas sensors, pigments, ceramics, and glass industry.
Copper (Cu): Atomic number (29), Atomic mass (63), uses - electrical equipment, Musical Instruments, Tools etc. Mercury (Hg): Atomic number (80), Atomic mass (200), uses - chemical industry, thermometers, barometers etc. Silver (Ag): Atomic number (47), Atomic mass (107), uses - Medicine, Jewelry etc.

Zinc sulphate (ZnSO₄) describes a family of inorganic compounds. Zinc displaces copper from copper sulphate and generates zinc sulphate solution when added to CuSO₄ solution because zinc is a more reactive metal that displaces less reactive metal from its solution. The chemical equation of the reaction, Zn + CuSO₄ → ZnSO₄ + Cu. Zinc Oxide (ZnO), it is an inorganic compound. In water, ZnO is a white powder that is insoluble.

Precipitation reaction can be defined as a chemical reaction occurring in an aqueous solution where two ionic bonds combine, resulting in the formation of an insoluble salt. Example - AgNO₃(aqueous) + KCl(aqueous) → AgCl(precipitate) + KNO₃(aqueous).

2FeSO₄ (Ferrous Sulfate) → Fe₂O₃ (Ferric oxide) + SO₂ (Sulfur dioxide) + SO₃ (Sulfur trioxide) . On heating strongly, the anhydrous Ferrous Sulfate decomposes to form Ferric oxide, sulfur dioxide and Sulfur trioxide.
Uses of Ferric Oxide - coloring agent for tablets and capsules in pharmaceutical industry, used as an abrasive in jewellry industry. It is an example of a decomposition reaction.

The reaction between lead nitrate and potassium iodide is a type of precipitation and double displacement reaction. Pb(N𝑂₃)₂ (Lead nitrate) + 2KI (Potassium iodide) → Pb𝐼₂ (Lead iodide) + 2KN𝑂₃ (Potassium Nitrate). The Lead Iodide is precipitated and Potassium Nitrate remains dissolved in the solution.

Balanced Chemical Equation - An equation where the number of atoms of each type in the reaction is the same on both reactants and product sides. Example - 3Fe + 4H₂O → Fe₃O₄ {Iron (II, III) oxide} + 4H₂ .

N𝑎₂S𝑂₄(Sodium Sulphate) + BaCl₂ (Barium Chloride) → BaSO₄ (Barium Sulphate) + 2NaCl (Sodium Chloride). Double displacement reaction - A double displacement reaction is a type of reaction where part of one reactant is replaced by part of another reactant.
Double displacement reaction - AB + CD → AD + CB. Example: AgNO₃ (Silver Nitrate) + NaCl (Sodium Chloride) → AgCl (Silver Chloride) + NaNO₃ (Sodium Nitrate).

Reactant - Substance that takes part in and undergoes change during a reaction. Products - Substances produced in the reaction. General equation - 2Mg (reactant) + O₂ → 2MgO (product)।