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 surface tension: the energy required to increase a liquid’s surface area by 1 m 2 -- water has a high surface tension due to HBFs a measure of the “tightness” of a surface’s “skin”

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

capillary action: the rise of liquids up narrow tubes -- adhesion _________ the liquid, while cohesion… “stretches” 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  r  r 2 = Liquid stops rising under this condition. gravity If tube diameter increases by a factor of 10: adhesion increases 10X; liquid’s weight increases 100X.

Will a “plug” of liquid continue inching its way up a tube? 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. Assume there is a plug that wants to break free… “No creeping plugs.” Adhesion forces pull it up. Plug drops until “up” adhesion equals gravity.