solvent-excluded volume

Solvent-excluded volume refers to the space around a molecule that solvent molecules cannot enter due to the molecule’s physical size and surface structure. Imagine a molecule as a shape with a boundary; solvent molecules are typically smaller but cannot penetrate this boundary because of repulsive interactions. This creates an effective “excluded” region where the solvent cannot go. Understanding this volume helps scientists grasp how molecules behave in solutions, such as how they fold, interact, or assemble, as it plays a key role in processes like protein stability and chemical reactions.