Hydrogen is one possible energy source for road vehicles in the future. One issue that still needs to be resolved is how the hydrogen will be stored inside the vehicle. A standard tank containing liquid hydrogen would need to be both pressurised and refrigerated. If such a tank were involved in a crash, it might rupture, causing hydrogen to escape very quickly and leading to an explosion.
Another option is a fuel tank filled with carbon nanotubes. In this design, the hydrogen inside the tank would be adsorbed onto the surface of the nanotubes at a pressure of no more than a few atmospheres.
(a(i))
About what width does a carbon nanotube have?
(a(ii))
What structural arrangement does the carbon in a nanotube have?
(a(iii))[4]
What forces might hold the hydrogen on the nanotube surface? Explain your answer.
(b)[1]
The hydrogen atoms in a fuel tank packed with nanotubes are closer together than they are in liquid hydrogen. Suggest one benefit of this.
(c)[4]
When a nanotube-packed fuel tank is full of hydrogen, there is a steady pressure of hydrogen in the tank. As hydrogen gas is taken out of the fuel tank to power the car, the pressure in the fuel tank falls only a little for some time. State Le Chatelier’s principle, and suggest how it explains this observation.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A width of a few nanometres (accept $0.5{-}10\,\mathrm{nm}$)” …