Mass transfer and chemical reactions in nanoscale particles under the assumption of the size dependence of the cohesive energy or the influence of the Laplace pressure are considered. A comparison of the above-mentioned approaches is given. It is shown that the use of the first or second of the abovementioned approaches can lead to a difference in the dependence of the rates of the aforementioned processes on the nanoparticle size. The influence of the confinement of ionic liquids within nanopores of supported ionic liquid membranes on the separation of gas mixtures is discussed. Considered regularities can be used for clarifying the physical mechanisms of the size effects, which take place in systems with nanoparticles and nanopores, and for the intensification of some processes in chemical engineering and nanotechnology. (C) 2018 Elsevier B.V. All rights reserved.