| Compound | Useful effects / Uses | Harmful effects |
|---|---|---|
| Dichloromethane (CH₂Cl₂) | • Used as a solvent for paints, varnishes and adhesives. • Used in paint removers and as a solvent in pharmaceutical industries. | • Its vapours can affect the central nervous system. • Prolonged exposure can be harmful to health. |
| Chloroform (CHCl₃) | • Used as a solvent for fats, oils, alkaloids, iodine, etc. • Earlier used as an anaesthetic. | • In air/light, it can form phosgene (COCl₂), a highly poisonous gas. • Therefore, it is stored in dark bottles with a little ethanol. |
| Tetrachloromethane / Carbon tetrachloride (CCl₄) | • Used as a solvent for fats, oils and resins. • Earlier used in fire extinguishers. | • Toxic to the liver and kidneys. • Harmful to the ozone layer. |
| Freons (CFCs) | • Used as refrigerants in refrigerators and air-conditioners. • Used as propellants in aerosol sprays. | • Cause depletion of the ozone layer. • UV radiation reaching Earth increases due to ozone depletion. |
| DDT | • Powerful insecticide. • Used to control mosquitoes and agricultural pests. | • Non-biodegradable, so it persists in the environment. • Accumulates in organisms and undergoes biomagnification. • Can harm birds and other wildlife. |
| Compound | Useful effects / Uses | Harmful effects |
|---|---|---|
| Iodoform (CHI₃) | • Used as an antiseptic and disinfectant. • Historically used for dressing wounds because of its antimicrobial action. • Has a characteristic yellow colour and smell. | • Can cause skin irritation on prolonged contact. • Its vapours can irritate the eyes and respiratory tract. • Excessive exposure can be harmful. |
Molecular Formula of All Compounds
| Compound | Molecular Formula |
|---|---|
| Dichloromethane | CH₂Cl₂ |
| Chloroform | CHCl₃ |
| Iodoform | CHI₃ |
| Carbon tetrachloride / Tetrachloromethane | CCl₄ |
| Freons (CFCs) | CCl₂F₂ (Freon-12, common example) |
| DDT | C₁₄H₉Cl₅ |
