Haloalkanes and Haloarenes MCQ
Before downloading Haloalkanes and Haloarenes MCQ you can enjoy the important information on Polyhalogens compounds.
1. Dichloromethane (CH2Cl2)
(A) Uses: It is used as
(i) A solvent in drug industry
(ii) Paint remover and propellant in aerosols
(iii) A cleaning agent for metals
(B) Environmental impact
(i) Its direct contact to our skin develops redness and burning sensation
(ii) It is harmful to our central nervous system
(iii) Its high level in air causes nausea, numbness in figure and toes
2. Trichloromethane CHCl3 (Chloroform)
Chloroform is a sweet-smelling liquid boiling point 334K, non-inflammable but its vapour causes unconsciousness When exposed to sunlight and air it slowly decomposes into phosgene (COCl2), a poisonous gas. It is therefore stored in closed dark coloured bottle completely filled so that air is kept out 2CHCl3 + O2 → 2COCl2+ 2HCl
(A) Uses: It is used
(i) As a solvent for fats, oils, varnishes, waxes, resins and rubber etc..
(ii) For the preparation of chloretone (a drug) and chloropicrin (insecticide).
(iii) As an anesthetic after being mixed with ether.
(iv) In the manufacture of Freon (refrigerant)
(B) Environmental impact
(i) On inhalation, it depresses the central nervous system an causes headache and dizziness.
(ii) Chronic exposure damages liver and kidneys.
(iii) On exposure to sunlight and air it slowly decomposes into phosgene.
(iv) Ethanol (1%) is added to retard the oxidation of phosgene into harmless ethyl carbonate.
(C) Tests of chloroform: It gives isocyanide test (Pungent smell). Pure CHCl3 does not give white precipitate with AgNO3, but with Tollen’s reagent, it gives grey precipitate of silver. On heating with Fehling’s solution, it gives brown precipitate
3. Tri-iodomethane CHI3 (Iodoform)
· It is a yellow crystalline solid pungent characteristic odour. Melting point is 392K and is steam volatile. It is used as an antiseptic for dressing wound
(A) Uses: It is used as
(i) As an antiseptic for dressing of wound.
(ii) In the manufacture of certain pharmaceuticals.
(B) Environmental impact
(i) When it comes in contact with skin, iodine is liberated which is responsible for antiseptic properties.
(ii) It has an objectionable smell.
4. Tetra chloromethane CCl4 (Carbon tetra chloride)
· It is a liquid, boiling point 350K, non-flammable, hence used as a solvent for fats, oils, waxes and resins etc. It is used as a fire extinguisher under the same name pyrene.
(A) Uses: It is used
(i) As a fire extinguisher.
(ii) As a solvent and also dry-cleaning.
(iii) In medicine as helminthicide for elimination of hook worm.
(B) Environmental impact
(i) Its vapours when breathed causes nausea, dizziness, vomiting and may cause damage nerve cells permanently.
(ii) On exposure it causes cancer, irregular heart beat and a person may go to coma.
(iii) Its vapour depletes ozone layer. Ozone hole permits the ultraviolet radiation to reach on earth and may cause skin cancer, eye disease and disorder, it may adversely affect our immune system.
Download More Notes:-
(1) S Block Elements :- Click Here
(2) Solid State :- Click Here
5. Freons (CFC’s): – Freons are small organic molecules containing C, Cl and F. The most common freons are CF2Cl (Freon -12) and CF3Cl (Freon -11)
(A) Uses (i) In air conditioning and domestic refrigerators for cooling purpose.
(ii) As propellants in aerosol and foams to spray out deodorants, cleaners and Insecticides. Halothane (CF3CHBrCl) is used as inhalation anesthetic.
(B) Environmental impact: – Most Freon eventually makes its way into the atmosphere where it diffuses unchanged into the stratosphere. In stratosphere, Freon is able to initiate radical chain reaction that can upset the natural ozone layer surrounding earth.
p,p’ – Dichlorodiphenyl trichloro ethane (DDT) · It is prepared by heating chloral with chlorobenzene in presence of conc H2SO4
(A) Uses:
(i) As an effective insecticide for mosquitoes, flies and crop pests.
(ii) As an antimalarial.
(B) Environmental impact: – It is non-biodegradable and its residue accumulates in environment, a cause of danger. It is not metabolized by the system and get deposited on the tissue, thus raises alarming danger. It is highly toxic to fish
