What happens to colloidal suspensions when heated?

In colloidal suspensions, heating can lead to changes in the stability of the colloidal particles. When exposed to heat, the increased kinetic energy can cause the particles to collide more frequently with each other. If the energy provided by the heat is sufficient, it can disrupt the forces that keep the colloidal particles suspended, leading to agglomeration or coagulation. This results in the formation of larger aggregates that can settle out from the suspension.

This process is significant because it illustrates the delicate balance that maintains the stability of colloids. Factors such as temperature, ionic strength, and the size of the particles all influence whether a colloid remains stable or if it coagulates upon heating. Therefore, when colloidal suspensions are heated, they can indeed undergo coagulation, which is the correct answer to the question.

Other options refer to different processes that do not accurately describe the typical behavior of colloidal suspensions when heated. For instance, colloids do not simply dissolve completely or become true solutions upon heating; they typically require different conditions and forces for those changes to occur. Similarly, not all colloidal suspensions evaporate quickly due to heating; this depends on the nature of the solvent and the specific colloid involved.