Question 1: Define a fullerene and describe its main structural feature.

Answer: A fullerene is a molecule composed entirely of carbon, taking the form of a hollow sphere, ellipsoid, or tube, with a structure based on hexagonal and pentagonal rings, such as C60 buckminsterfullerene.

Question 2: Explain why graphene is considered a two-dimensional material with remarkable electrical properties.

Answer: Graphene is a single layer of carbon atoms arranged in a hexagonal lattice, making it two-dimensional. Its delocalised π-electrons enable excellent electrical conductivity, making it highly conductive and useful in electronic applications.

Question 1: Calculate the molecular surface area of a single C60 fullerene molecule, given that the approximate diameter of C60 is 0.7 nanometres. Use the formula for the surface area of a sphere: 4πr².

Answer: Surface area ≈ 4 × π × (0.35 nm)² ≈ 4.87 nm²

Question 2: If graphene has a molar mass of approximately 12 g/mol per carbon atom, what is the mass of 1 mole of a 10 cm² sheet of graphene, assuming a surface density of 3.8 × 10¹⁵ atoms/cm²?

Answer: Mass ≈ 12 g/mol × (3.8 × 10¹⁵ atoms/cm² × 10 cm²) / (6.022 × 10²³ atoms/mol) ≈ 0.76 g

Question 1: Outline the key variables, safety precautions, and basic procedure for testing graphene's electrical conductivity.

Answer: Key variables include the length and thickness of the graphene sample, voltage applied, and current measured. Safety precautions involve avoiding short circuits and handling electrical equipment safely. The procedure involves connecting the graphene sheet in a circuit with a power supply and ammeter, then measuring current at different voltages to assess conductivity.

Question 1: A researcher produces a mixture containing 5% C60 fullerenes by weight. If 10 grams of the mixture are processed, how many grams of C60 are present? Discuss one method to increase the yield of C60 during synthesis.

Answer: There are 0.5 grams of C60 in the mixture. To increase yield, controlled combustion or arc-discharge methods with optimised conditions can be used to favour fullerene formation.

Question 1: Explain the structural differences between fullerenes and graphene, and discuss how these differences influence their respective properties and potential applications.

Answer: Fullerenes are spherical or ellipsoidal molecules composed of carbon atoms arranged in pentagons and hexagons, forming a closed cage structure. Graphene is a single, flat sheet of hexagonally arranged carbon atoms with delocalised electrons. The spherical structure of fullerenes allows them to act as molecular cages, useful in drug delivery and materials science, while the planar structure of graphene provides exceptional electrical conductivity, strength, and flexibility, making it ideal for electronic devices, sensors, and composite materials.

Question 1: Identify one real-world application of fullerenes and one of graphene, explaining their roles in each application.

Answer: Fullerenes are used in drug delivery systems because of their ability to trap molecules inside their cage structures. Graphene is utilised in flexible touchscreens and high-speed electronic circuits due to its excellent electrical conductivity and mechanical strength.