(a) Write two points of difference in the structures of diamond and graphite.
(b) Explain why graphite can be used as a lubricant but diamond cannot.
(c) Explain why diamond can be used in rock drilling equipment but graphite cannot.
(d) State one use of diamond which depends on its 'extraordinary brilliance' and one use of graphite which depends on its being 'black and quite soft'.
|Sl.No||Structure of Diamond||Structure of Graphite|
|1.||Each carbon atom is joined to four other carbon atoms by strong covalent bonds to form a regular tetrahedron.||Each carbon atom is joined to three other carbon atoms by strong covalent bonds to form flat hexagonal rings.|
|2.||Compact and rigid structure (hard)|| |
Layered structure (soft)
(b) Because of its softness and non-volatile nature, graphite is used as a lubricant in the fast moving parts of a machinery. It is used for lubricating the parts of machinery which operate at high temperatures. Diamond, on the other hand, is an extremely hard substance; therefore, it cannot be used as a lubricant.
(c) As diamond is extremely hard, it can be used to cut and grind other hard materials or metals. Hence, it is used in rock-drilling equipment to drill holes in the rocky layers of the Earth. Graphite being soft cannot be used to cut or grind.
(d)(i) Diamonds are used in making jewellery because of their extraordinary shine and texture.
(ii)Graphite is used in making pencil leads (the black core of pencils) because of its black colour and softness.