Surface Tension


Surface Tension

Next to mercury, water has the highest surface tension of all commonly occurring liquids. Surface tension is a manifestation of the presence of the hydrogen bond. Those molecules of water that are at the surface are strongly attracted to the molecules of water below them by their hydrogen bonds. If the diameter of the container is decreased to a very fine bore, the combination of cohesion, which holds the water molecules together, and the adhesive attraction between the water molecules and the glass container will pull the column of water to great heights. This phenomenon is known as capillarity. This is a key property that allows trees to stand high, for example, because surface tension stiffens stems and trunks. Plants "wilt" because they are unable to acquire sufficient water to maintain the required surface tension. And, of course, water droplets (rain) and fog condensing as droplets on surfaces are a function of water's surface tension. Without this property, water would be a slimy coating and cells would not have shape. Surface tension decreases with temperature and salinity.

Video: Amusing Surface Tension Experiment (02:39)

Please take a few minutes to watch this amusing video to learn more about the surface tension of water.

Amusing Surface Tension Experiment
Click here for a transcript of the Amusing Surface Tension Experiment video

Inside your clicky pen is a science experiment waiting to spring forth. Fill a cup with water. Place the spring from your clicky pen ever so gently into the water it floats. Why? Because the middle of the spring is lighter than water? No Diana, you buffoon, metal is not lighter than water and as much as this spring resembles the Titanic one of them is doing a better job of staying afloat. But wait now I will activate the evil goo of death okay? Now before I bring travesty and devastation to this display of tensile forces I will explain it because it's cool enough to destroy the water holds up the spring because the h2o molecules on the surface of the water are bonded together quite tight. These surface molecules have fewer neighbors than the rest of the molecules and the one could say they're exposed like parts of Janet Jackson I never wanted to see. Therefore they use all their bonding power to hold on tight to their neighbors below and on all sides so consequently. They're pulled down which creates a pressure on the surface, pulling it toward the rest of the water in the cup stay with me don't leave my page yet this pressure creates a cushion or net that the spring can rest on comfortably and now for the destruction of it all and don't even attempt to stop me because in my hands is soap the soap that will break the hydrogen bonds and the molecules on the surface of the water because my silk molecules will attach to the h2o and steal them away from their girlfriends and childrens and wives. I just said childrens. Well, there you have it.

Credit: Physics Girl