What term describes the movement of organic compounds through plastic pipe walls under pressure?

• A. Osmosis
• B. Water Hardness, Permeation
• C. Diffusion
• D. Organic compounds, Permeation

Answer: (D)

The movement of organic compounds through plastic pipe walls under pressure is called permeation. In plastics, permeation happens when an organic molecule dissolves into the polymer (solubility) and then diffuses through the polymer matrix (diffusivity) to the other side. The overall rate depends on how soluble the compound is in the plastic, how fast it can move within the plastic, the thickness of the pipe wall, and the pressure driving the transfer. This is different from diffusion, which describes movement within a medium itself, and from osmosis, which is the movement of water across a semipermeable membrane due to osmotic pressure. Permeation specifically describes transfer through the barrier material, such as a plastic pipe wall.