Question

(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'.

Answer 1

a)

Two points of difference in the structure of diamond and graphite are:

1)

✤Diamond has many tetrahedral structures of carbon atoms joined together tightly.

✤graphite has many hexagonal sheets of carbon atoms joined together somewhat loosely.

2)

✤diamond don't have any free electron in its structure.

✤graphite have free electrons in is structure.

b)

graphite can act as a lubricant due to loosely intact carbon atoms which are slippery hexagonal sheets. while diamond have tightly packed carbon atoms which form a very very hard material.

c)

diamond is used in rock drilling machines due it's hardness, and tightly packed. while graphite is soft so can't be used in this work.

d)

diamond is used in jewellery due to it's brilliance.

graphite is used for making pencil due to it's blackness and softness.

Answer 2

Explanation:

• (a) In diamond, every carbon is bonded with four other carbons, whereas in graphite each carbon is bonded with only three carbon atoms.
• Tetrahedral arrangement is observed in a diamond crystal, whereas flat hexagonal ring structure is observed in a graphite crystal.
• (b) Graphite can be used as a lubricant because of its softness and layered structure. It has the layers that are attached to each other by means of weak force of Van der Waal due to which they slide over, whereas the diamond is very strong and cannot be used as lubricant.
• (c) Graphite is very soft, whereas diamond is rigid, very strong and hard. This is the reason why graphite cannot be used for drilling, whereas diamond is used for drilling.
• (d) Diamond are useful for making jewellery, whereas graphite is used for making pencil leads or pencil cores.