Why does capillary action occur

Capillary action is an effect caused by the interactions of a liquid [e. On the video below is this process explained:. The capillary action depends on adhesion [attraction of molecules of one kind to molecules of a different kind] which enables water to go upwards through thin glass tubes and cohesion [attraction of molecules to other molecules of the same kind] interactions between water molecules. In this case, addhesion forces are much stronger than the cohesion forces so water can move upward in a capillay tube.

Why does capillary action occur? Marta O. Feb 14, Capillary action or capillarity describes the ability of a liquid to flow against gravity in a narrow space such as a thin tube. Cohesion — the attractive forces between similar molecules or atoms, in our case the molecules or atoms of the liquid.

Water, for example, is characterized by high cohesion since each water molecule can form four hydrogen bonds with neighboring molecules. Adhesion — the attractive forces between dissimilar molecules or atoms, in our case the contact area between the particles of the liquid and the particles forming the tube. The capillarity of the liquid is said to be high when adhesion is greater than cohesion, and vice versa. Hence, knowledge of the liquid is not sufficient to determine when capillary action will occur, since we must also know the chemical composition of the tube.

These two, together with the contact area the tube's diameter , comprise the key variables. Essentially, cohesion and adhesion are the "stickiness" that water molecules have for each. Skip to main content. Search Search. Water Science School. Capillary Action and Water. Water Properties Information by Topic Learn more.

Smaller diameter tubes have more relative surface area inside the tube, allowing capillary action to pull water up higher than in the larger diameter tubes Credit: Dr. Keith Hayward. Learn more about capillary action and related water properties.

Date published: October 22, Filter Total Items: 5. Year Select Year Apply Filter. Date published: June 28, Attribution: Water Resources. Date published: June 6, Date published: May 22, Date published: August 9, Date published: June 5, Below are publications associated with capillary action and related water properties.

Filter Total Items: 1. Year Published: Soil water retention and maximum capillary drive from saturation to oven dryness This paper provides an alternative method to describe the water retention curve over a range of water contents from saturation to oven dryness. Morel-Seytoux, Hubert J. View Citation. Below are multimedia items associated with capillary action and related water properties. Filter Total Items: 4. List Grid. February 2, Narrower tube openings allow capillary action to pull water higher.

Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a