`` NEWTON: Surface Tension
 
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Name: Onur
Status: student
Grade: 9-12
Country: Germany
Date: Summer 2013


Question:
I have difficulties understanding how surface tension develops in water. The sources that I have read,they all say so called unbalanced intermolecular forces at the water air interface, that is clear. Then it says they jump into deeper layers which is more favorable from energy view point. The points that are needed to be clarified in my mind: 1) Since fluids are incompressible, where do these surface molecules find a place to occupy in deeper layers? 2) Let us assume they find some place. Do these molecules, which left on the surface, attract back the molecules that are now in bulk fluid? 3) How does this whole process cause surface tension? Are the remaining molecules that are attracted to each other, stronger? What is the reason for the surface molecules to behave like a stretched membrane?

Replies:
Hi Onur,

Thanks for the questions. For question 1, the surface molecules do not occupy deeper layers. For question 2, the surface molecules attract molecules in the bulk fluid. For question 3, the surface molecules behave like a stretched membrane since not all of the hydrogen bonding sites are occupied. Water has four possible sites for hydrogen bonding.

I hope this helps. Please let me know if you have more questions. Thanks Jeff Grell


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