Question

Почему вода не смачивает жир?

Answer 1

Вода (или любая другая жидкость) смачивает какую-либо поверхность только в том случае, если сила взаимодействия молекул воды (жидкости) с молекулами (или ионами) поверхности больше, чем сила взаимодействия молекул воды (жидкости) между собой. В случае жира (в качестве поверхности) взаимодействие молекул воды с молекулами жира очень слабое, поэтому и не смачивает.

Answer 2

Why doesn't water wet grease?

Water does not wet grease due to the difference in their molecular properties. The molecular structure of water and grease is such that they have different intermolecular forces and polarities, which affects their ability to mix or interact with each other.

Water is a polar molecule, meaning it has a positive and negative end due to the unequal distribution of electrons. This polarity allows water molecules to form hydrogen bonds with each other and with other polar substances. When water comes into contact with a polar substance, such as another water molecule or a polar solid, it can easily spread and wet the surface.

Grease, on the other hand, is a nonpolar substance. It consists of long hydrocarbon chains that do not have a significant charge separation. Nonpolar substances like grease do not readily mix with polar substances like water because the intermolecular forces between them are weaker. Instead of spreading and wetting the surface, water tends to bead up and form droplets on the surface of grease.

The inability of water to wet grease is due to the difference in polarity and intermolecular forces between the two substances. Water's polar nature allows it to interact strongly with other polar substances, while grease's nonpolar nature prevents it from easily mixing with polar substances like water.