Students are presented with a short lesson on the difference between cohesive forces (the forces that hold water molecules together and create surface tension). This lesson will focus on a few that can be easily explained due to intermolecular forces, mainly surface tension, capillary action, viscosity, and physical changes. Surface Tension and Capillarity. Introduction. Due to molecular attraction, liquids possess certain properties such as cohesion and adhesion. Cohesion means.
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Surace Tension and Capillary Action
Antoine Molin,pages ff Archived at the Wayback Machine. Montanario opposita circa elevationem Humoris in canaliculis, etc.
Montanari's opposition regarding the elevation of liquids in capillaries is utterly refuted. Adrian Vlacq,pages 3—7 Archived at the Wayback Machine. Philosophical Transactions of the Royal Society of London, Self-published, pages — Francis Hauksbee "An account of an experiment touching the ascent of water between two glass planes, in an hyperbolick figure," Philosophical Transactions capillarity and surface tension the Royal Society capillarity and surface tension London, Josia Weitbrecht "Tentamen theoriae qua ascensus aquae in tubis capillaribus explicatur" Archived at the Wayback Machine.
Theoretical essay in which the ascent of water in capillary tubes is explainedCommentarii academiae scientiarum imperialis Petropolitanae Memoirs of the imperial academy of sciences in St. Measuring Surface Tension One method to measure the surface tension of a liquid is to measure the height the liquid rises in a capillary tube.
By setting the two forces above equal, we find the surface tension to be: For pure water and clean glass, the contact angle is nearly capillarity and surface tension. However, you must use pure water and extremely clean glass to get this result.
Usually, the measured surface tension is at least half of this number. The convex or concave upper surface of a column of liquid, the curvature of which is caused by surface tension.
- Surface Tension, Capillary Action, Viscosity & Physical Changes |
- Capillarity—Measuring Surface Tension - Lesson - TeachEngineering
The property of the surface of a liquid capillarity and surface tension allows it to resist an external force.
This property is caused by cohesion of like molecules and explains many of the behaviors of liquids. Associated Activities Exploring Capillary Action - Students observe glass-water menisci and explain the shape in terms of adhesive forces. Using capillary tubes, they see water climbing due to capillary action.
Capillarity and surface tension, teams design and test "capillary siphons" that can be used to filter water.
Measuring Surface Tension - Capillarity and surface tension use capillary action to measure surface tension. They find the average surface tension and calculate the statistical error. Ask the students and discuss as a class: Who can remind the class what we have already learned about surface tension?
When you water a plant, no matter where in the pot you pour in the water, the water reaches all of the roots. How does it do this? Why does a paper towel absorb water, while a piece of plastic does not?
Capillary action - Wikipedia
Ask students to work individually or in pairs or small groups to answer the following two problems. Review and discuss answers as a class or have students compare answers in order to gauge their level of understanding before moving on to conduct capillarity and surface tension associated lab activity.
See solution if necessary.