EasyChemistryHigh School (9–10)GeneralCarbon and Its Compounds › Covalent Bonding and AllotropesConceptualBoard Exam
Which form of carbon, diamond or graphite, suits each use best? …
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Which form of carbon, diamond or graphite, suits each use best? Give a reason for each.
- The tip of a dentist's drill.
- The brushes that carry current into a spinning electric motor.
- A crucible for melting metals, which must stand great heat.
- A stone in a ring.
Need a reminder? The key ideaShow
Allotropes are forms of one element. Diamond: each atom bonded to four others, very hard, no free electrons. Graphite: layers of hexagons, each atom bonded to three, soft and slippery, conducts. Fullerene : a cage of atoms. All burn to carbon dioxide: .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Diamond. It is the hardest natural substance, because every atom is held by four strong bonds.
Step 2. (b) Graphite. It conducts electricity, and its slippery layers rub smoothly on the spinning part.
Step 3. (c) Graphite. It has a very high melting point and is far cheaper than diamond.
Step 4. (d) Diamond. It is hard, so it keeps its shine, and it bends light strongly.
Answer: (a) diamond; (b) graphite; (c) graphite; (d) diamond.
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