What technique allows small molecules to diffuse through semipermeable membranes?

The technique that allows small molecules to diffuse through semipermeable membranes is dialysis. Dialysis involves the passive movement of solutes across a membrane that selectively permits certain substances to pass through while restricting others based on size and concentration gradients. In this process, small molecules can move from an area of higher concentration to an area of lower concentration, achieving equilibrium.

This is particularly important in biological systems and medical applications, such as in kidney function and artificial kidney machines, where the removal of waste products and excess substances from the blood is necessary. Dialysis is specifically designed for separating smaller particles from larger ones, making it essential for processes where the selective removal or separation of specific ions or molecules is required.

In contrast, osmosis specifically refers to the movement of water across a semipermeable membrane rather than small solutes. Filtration is typically a physical separation technique that may not apply to the selective diffusion of molecules based on size and concentration. Dilution, on the other hand, is a process that reduces the concentration of solutes in a solution but does not involve any selective membrane or diffusion process.