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Adhesion – the attraction of molecules or compounds for other molecules of a different kind; Specific heat capacity – the amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius; Heat of vaporization – the amount of energy needed to change one gram of a liquid substance to a gas at constant temperature
2 O; one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. [26] Water is a tasteless, odorless liquid at ambient temperature and pressure. Liquid water has weak absorption bands at wavelengths of around 750 nm which cause it to appear to have a blue color. [4]
A similar concept applies to liquid–gas phase changes. [7] Water is an exception which has a solid-liquid boundary with negative slope so that the melting point decreases with pressure. This occurs because ice (solid water) is less dense than liquid water, as shown by the fact that ice floats on water.
The same surface tension demonstration can be done with water, lime water or even saline, but only on a surface made of a substance to which water does not adhere. Wax is such a substance. Water poured onto a smooth, flat, horizontal wax surface, say a waxed sheet of glass, will behave similarly to the mercury poured onto glass.
Adhesion is the tendency of dissimilar particles or surfaces to cling to one another. ( Cohesion refers to the tendency of similar or identical particles and surfaces to cling to one another.) The forces that cause adhesion and cohesion can be divided into several types.
This occurs between water and glass. Water-based fluids like sap, honey, and milk also have a concave meniscus in glass or other wettable containers. Conversely, a convex meniscus occurs when the adhesion energy is less than half the cohesion energy. Convex menisci occur, for example, between mercury and glass in barometers [1] and thermometers.
Water bead on a fabric that has been made non-wetting by chemical treatment. Wetting is the ability of a liquid to displace gas to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. [1]
Water is passively transported into the roots and then into the xylem. The forces of cohesion and adhesion cause the water molecules to form a column in the xylem. Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves the plant by diffusion through the stomata