Final answer:
Adhesives in solvents form dispersions that harden as the solvent evaporates due to increased adhesive forces between the adhesive and the bonding surface.
Step-by-step explanation:
When discussing dispersions of active adhesive in a solvent, we are referring to a mixture where the adhesive particles are spread out and suspended within the solvent. As the solvent evaporates, intermolecular forces, such as adhesive forces, come into play and cause the adhesive to interact with the surface it's applied to, leading to hardening. This process is crucial for materials like wood glue which, upon solvent evaporation, leaves the adhesive to harden and firmly bond surfaces together. The hardening occurs due to the loss of solvent, which initially provided the necessary fluidity for application, and subsequent interactions between the adhesive particles and the surface, caused by attractive adhesive forces that are stronger than the cohesive forces within the adhesive itself.