Question

What are amorphous forms of carbon?

Answer 1

Hint: As we know that carbon possess catenation property and pi-pi bond formation so it can exist in crystalline as well as amorphous forms where an amorphous form of carbon is free and reactive having localised pi-electrons and are without any crystalline structure.

Complete Step by step answer:
- Carbon shows allotropism due to the catenation property and pi-pi bond formation. It exists in two allotropic forms that are crystalline and amorphous forms. An amorphous form of carbon is free and reactive having localised pi-electrons. The amorphous forms of carbon involve coal, charcoal and lamp-black.
- Let us talk about coal first, it is the crude form of carbon and forms in nature as a result of slow decomposition of vegetable matter under the influence of heat, pressure and limited supply of air. The successive stages of transformation include peat, lignite, bituminous, steam coal and anthracite. Among these bituminous is the hard stone, burns with smoky flame and anthracite burns without a smoky flame.
- When coal is heated in air it gives carbon dioxide and water and when it is heated without air it undergoes destructive distillation and results in the formation of coke, coal tar, coal gas and ammonium solution. Coke is the purest form of carbon among them all.
- The second amorphous form is charcoal which includes wood charcoal, bone charcoal and sugar charcoal. When wood is heated in a limited supply of air it gives a soft, black, porous substance called wood charcoal. It is a bad conductor of electricity and a smokeless fuel. Then comes sugar charcoal which is the purest form of charcoal and used as a reducing agent to extract metals from their oxides and the bone charcoal is obtained by destructive distillation of bones resulting in bone oil, bone charcoal and pyridine.
- Lastly the lamp black or soot or carbon black which is obtained by burning carbon rich substances like kerosene, petroleum, turpentine oil, acetylene etc in a limited supply of air.

Note: Some uses of amorphous forms of carbons: bone charcoal is used as a decolourising agent, lamp black is used in cosmetics, printing ink and gunpowder, sugar charcoal is used to make artificial diamonds.