Some Properties of Liquids viscosity a liquids resistance

Some Properties of Liquids viscosity: a liquid’s resistance to flow -- high viscosity = high resistance to flow -- depends on IMFs -- as temp. increases, viscosity decreases

Molecules on a liquid’s surface experience a net inward force -- this reduces surface area and “packs together” m’cules on surface tension: the energy required to increase a liquid’s surface area by 1 m 2 -- a measure of the “tightness” of a surface’s “skin” -- water has a high surface tension due to HBFs

cohesive forces: IMFs that bind. . . similar m’cules to each other adhesive forces: IMFs that bind. . . a substance to a surface -- their relative magnitude determines the shape of a meniscus: H 2 O adhesion > cohesion meniscus: Hg adhesion < cohesion

capillary action: the rise of liquids up narrow tubes “stretches” the liquid, -- adhesion _____ while cohesion… keeps it together In green plants, capillary action draws water through narrow tubes, collectively called xylem.

Why does liquid go up narrow tubes farther than up thick tubes? adhesion force 2 pr gravity pr 2 = gravity If tube diameter increases by a factor of 10: Liquid stops rising adhesion increases 10 X; under this condition. liquid’s weight increases 100 X.

Will a “plug” of liquid continue inching its way up a tube? Assume there is a plug that wants to break free… Adhesion forces pull it up. As soon as plug breaks free from rest of liquid, “down” adhesion forces appear, which equal “up” adhesion forces. But there’s also gravity, so “down” wins. Plug drops until “up” adhesion equals gravity. “No creeping plugs. ”