Viscous liquid
Explanation
Coal Tar is a byproduct obtained during the processing of coal to produce coke, a process known as destructive distillation.
- Physical Nature: It is a thick, black, opaque liquid. Due to its high resistance to flow, it is described as a viscous liquid.
- Composition: It is a mixture of about 200 different carbon compounds and possesses a characteristic unpleasant smell.
- Usage: Though a liquid, it serves as a raw material for synthesizing various substances, including synthetic dyes, drugs, explosives, perfumes, plastics, and paints. Historically, it was used for metalling roads, though bitumen (a petroleum product) has largely replaced it.
Key Takeaway: Coal tar is a thick, black, viscous liquid byproduct of coal processing, distinct from solid coal or gaseous coal gas.