The following questions refer to the diagram below.
Answer the following questions using the gases listed below.
hydrogen (H2) oxygen (O2) helium (He)
nitrogen (N2) methane (CH4) carbon monoxide (CO)
Each gas may be chosen once, more than once, or not at all
(a) Which two gases, when placed into A and B respectively, will cause the water level at P to move up initially? Explain your answer.
(b) What would be observed in the diagram above if A is helium at room
temperature and B is helium at 60°C? Explain your answer.
(a) A: oxygen
Oxygen has higher relative molecular mass than air, faster outward diffusion of air.
Hydrogen/methane/helium has a lower relative molecular mass than air, faster inward diffusion of gas.
(b) Water level at P rises while water level at Q drops.
Helium at higher temperature has higher kinetic energy and diffuses faster into the porous pot.