3 This question is about materials and their properties
3-1 Figure 3 shows a carbon nanotube.
Figure 3
The structure and bonding in a carbon nanotube are similar to graphene.
Carbon nanotubes are used in electronics because they conduct electricity.
Explain why carbon nanotubes conduct electricity.
[2 marks]
ANSWER
Carbon nanotubes conduct electricity because of their intrinsic property as High electrical conductance – this is due to some of the electrons being delocalized throughout the structure and carries charge.
3-2 Figure 4 shows a badminton racket
Figure 4
Table 1 shows some properties of materials.
The materials could be used to make badminton racket frames.
Table 1
Evaluate the use of the materials to make badminton racket frames Use Table 1.
[4 marks]
ANSWER
Wood is the least dense so lightest to use whereas aluminium is the most dense so will make the racket too heavy;
Carbon nanotube is the strongest so least likely to break whereas wood / aluminium are too weak so the racket will break more easily;
Carbon nanotube is the stiffest so least likely to bend out of shape whereas wood / aluminium are not very stiff so could bend out of shape.
3-3 Zinc oxide can be produced as nanoparticles and as fine particles.
A nanoparticle of zinc oxide is a cube of side 82 nm.
Figure 5 represents a nanoparticle of zinc oxide
Figure 5
Calculate the surface area of a nanoparticle of zinc oxide. Give your answer in standard form.
[3 marks]
ANSWER
= 6 x (82 x 82)
= 4034nm2
3-4 Some suncreams contain zinc oxide as nanoparticles or as fine particles. Suggest one reason why it costs less to use nanoparticles rather than fine particles in sun creams.
[1 mark]
ANSWER
Less zinc oxide is needed to have the same effect because of greater surface area to volume ratio.
