Final answer:
Dewdrops made of saltwater may differ from those of pure water by leaving behind salt residues as they evaporate and potentially have a different surface tension affecting their size and shape. The dissolved ions in saltwater can also alter the intermolecular interactions compared to pure water.
Step-by-step explanation:
The question concerns how dewdrops of salt water may differ from those of pure water. Dewdrops form when water vapor undergoes condensation, typically in conditions where the air is saturated with moisture and the temperature drops, such as during the early morning or at night. As the water vapor condenses, it forms tiny beads of water on surfaces. In the case of saltwater, the process of evaporation leaves behind the salt which does not evaporate with the water. Therefore, dewdrops formed from salt water may leave behind salt residues as they evaporate, potentially altering their appearance, where you may observe crystalline structures once the droplet evaporates completely.
There is also the consideration of the surface tension of salt water, which may be different from that of pure water due to the presence of dissolved ions. This can potentially affect the size and shape of the dewdrops. Furthermore, the attraction between water molecules and the ions in salt water may be less pronounced than in pure water, where intermolecular attractive interactions are solely between water molecules.
In other examples, such as rain falling on a newly waxed car, we observe that the water forms round beads due to the nonpolar (water repelling) surface of the wax and the surface tension of the water. Similar effects could be seen with saltwater drops, although they may not be as pronounced or round due to the interactions between water and the dissolved salts.