4 Markers

Question 1

Describe how a student can obtain pure dry crystals of salt from a salt solution?

Answer 1

• heat/boil the solution
• evaporate some of the water
• leave/cool (the solution to crystallise)
• filter/pour off the excess liquid (to obtain crystals)
  -suitable drying method: (eg heat in an oven/leave to dry/use paper town)

Question 2

C60Fullerene is a simple molecular substance made of 60 carbon atoms.
Explain why C60fullerene has a much lower melting point than diamond and graphite.

Answer 2

• C60fullerene has weak forces between the molecules / weak intermolecular forces
• less energy needed to overcome the forces
• diamond and graphite have strong covalent bonds between atoms
• more energy needed to overcome the covalent bonds