Railway Science (Chemistry-Miscellaneous) (Part-II)

Iodine test is a chemical reaction based identification test for starch. Add Iodine - KI (Potassium Iodide) reagent to a solution or directly on a potato or other materials that contains carbohydrates (bread, flour).
A blue - black color results if starch is present. If starch amylose is not present, then the color will stay orange or yellow.

Example - Calcium (atomic number 20), and argon (atomic number 18) but the mass number of both these elements is 40. Isotopes - atoms having the same atomic number but different mass number.
Example - Hydrogen atom has three atomic species, namely protium deuterium and tritium. The atomic number of each one is 1, but the mass number is 1, 2 and 3, respectively. Isotones - Atoms having equal number of neutrons. Example - ³⁶₁₆S, ³⁷₁₇Cl, ³⁸₁₈Ar.

Aqua-regia - A chemical solution that is obtained by mixing one part nitric acid (concentrated) and three parts hydrochloric acid (concentrated). It can also dissolve - palladium (Pd), gallium (Ga), titanium (Ti).
Chemical formula of other Compounds : Sulphuric acid - H₂SO₄ , Sodium hydroxide - NaOH, Ammonium hydroxide - NH₄OH.

The water molecules that are present in the crystals are called water of crystallization. Blue vitriol (CuSO₄ .5H₂O) - called copper sulfate pentahydrate, contains 5 moles of water of crystallization.

Osmotic Concentration - The measure of solute concentration, defined as the number of osmoles of solute per litre of solution.
Osmotic Pressure - The minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane.
Turgor Pressure - Pressure exerted by fluid in a cell that presses the cell membrane against the cell wall.
Wall pressure - Pressure exerted by the cell wall against the turgor pressure.

Ozone-depleting substances (ODS) include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, Hydro Bromo fluorocarbons.
The ozone layer in the stratosphere :- Affected by the increase in the atmospheric concentration of CFC (chlorofluorocarbons).
Halon - liquefied, compressed gas that stops the spread of fire by chemically disrupting combustion.
Methyl Chloroform - Colourless liquid with an Ether-like odour. It is used in degreasing, as a solvent and spot cleaner, and in making other chemicals. Methyl Bromide - A colourless, nonflammable, highly toxic gas (readily liquefied) belonging to the family of organic halogen compounds.

Electronegativity - It is a chemical property that describes the tendency of an atom in a molecule to attract electrons toward itself. On the periodic table, electronegativity generally increases as move from left to right across a period and decreases as move down a group. Top electronegative elements are - Fluorine (F), Oxygen (O), Nitrogen (N), Chlorine (Cl), and Bromine (Br).

Coke - It is a grey, hard, and porous coal-based fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air. It is used in the manufacture of steel and in the extraction of many metals.
Destructive distillation - An irreversible chemical change caused by the action of heat in the absence of air.

Saturated fat - They are solid because they are saturated with hydrogen molecules and contain only single bonds between carbon molecules. It is one of the unhealthy fats. Foods like butter, palm and coconut oils, cheese, Meat and dairy products have high amounts of saturated fat.
Monounsaturated fat - A type of dietary fat. It is one of the healthy fats. These fats are liquid at room temperature but start to harden when chilled. Polyunsaturated fats - A type of healthy fat that includes omega-3 and omega-6 fatty acids, which are essential for brain function.

Chemical Formula of Potassium sulphate - K₂SO₄ . Some important chemical formula - Baking soda (NaHCO₃) - Sodium Bicarbonate, Blue vitriol (CuSO₄ .5H₂O) - copper sulfate pentahydrate, Washing Soda (Na₂CO₃ .10H₂O) - Sodium Carbonate Decahydrate, Gypsum (CaSO₄ .2H₂O) - Calcium sulphate dihydrate, Fitkari [K₂SO₄ .Al₂(SO₄)₃ .24H₂O] - Potassium aluminum sulfate.