Special Sub-Topic: Hydrogen Compounds
|Hydrofluoric acid, besides reacting with metals, also uniquely reacts with another substance. Name the substance. |
Glass. Hydrofluoric acid, which is the solution of hydrogen fluoride (HF) in water attacks glass and hence it is used to etch it. It does not attack plastic and thus is stored in containers of PTFE (Poly-tetra-fluoro-ethylene),a type of plastic.
|Which hydrogen compound gives urine its characteristic stench?|
Ammonia. Ammonia (NH3) is a colourless gas with a pungent smell and is highly soluble in water. The nitrogenous wastes excreted by our bodies combine with water in the kidneys to form urine, which is a mixture of various compounds including ammonia, which gives urine its smell. Ammonia has many industrial uses and is manufactured industrially by the Solvay Process.
|What is prussic acid associated with?|
Poison. Prussic acid, which is a solution of hydrogen cyanide (HCN) in water, is one of the most potent and quick-acting poisons known to man. It is a colourless liquid, smelling of bitter almonds.
|The presence of which gas causes explosions in coal mines?|
Methane. Methane or marsh gas (CH4) is the simplest hydrocarbon and occurs in natural gas and in coal mines. In coal mines it combines with oxygen of the air to form fire-damp, an explosive mixture.
|Which compound is used in cosmetic preparations to bleach facial and body hair?|
Hydrogen peroxide. Hydrogen peroxide (H2O2) is a natural bleaching agent and is used mixed with water in cosmetic preparations. When pure, hydrogen peroxide is a thick, syrupy liquid.
|What is the characteristic smell of hydrogen sulphide gas?|
Rotten eggs. When any compound having sulphur in the form of sulphides reacts with a dilute acid, hydrogen sulphide (H2S) is formed. This forms the basis of qualitative chemical analysis to determine the presence of sulphur in compounds. Hydrogen sulphide is also produced naturally by the decay of sulphur-containing organic matter and is found in some mineral springs.
|Which is the most important industrial acid?|
Sulphuric acid. Sulphuric acid (H2SO4) is a colourless, oily and corrosive liquid. It is the most industrially used acid being employed in fertilizer, pharmaceutical, cosmetic, electrical and chemical industries as a raw material.
|What is carbolic acid used for?|
Disinfectant. Carbolic acid or phenol(C6H5OH) is a corrosive and poisonous liquid which is mixed with a large volume of water so as to render it safe for humans. It is the basis of phenyl which is the commonest disinfectant used in homes and hospitals. Carbolic acid is also used for preparing special bacteria-destroying soaps.
|Acetic acid is used in preparing which common household product?|
Vinegar. Acetic acid (CH3COOH) is a pungent smelling liquid. Vinegar is manufactured from acetic acid produced by oxidation of ethyl alcohol.
|What is the most common hydrogen compound on Earth?|
Water. Water (H2O) covers over 70% of the earth's surface and comprises nearly 85% of our bodies. Without it no life would have been possible.
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