(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’.
(a) Diamond:
(i) Each carbon atom is linked to four other carbon atoms.
(ii) A diamond crystal has a tetrahedral arrangement of carbon atoms.
Graphite:
(i) Each carbon atom is joined to only three other carbon atoms.
(ii) A graphite crystal has flat hexagonal rings structure.
(b) Due to its softness, powdered graphite can be used a lubricant whereas diamond being extremely hard can not be used as lubricant.
(c) Due to its rigid structure, diamond is the hardest known substance to man. Hence, it is used in rock drilling equipment but graphite is soft and hence not used in rock drilling equipment.
(d) Diamonds are used for making jewellery.
Graphite is used for making pencil cores or ‘pencil leads’.