Measuring Surface Tension of Liquid | Methods & Units

In summary, to measure the surface tension of a liquid, there are several methods that can be used including the Du Nuoy ring method, Wilhelmy plate method, and measuring the velocity and wavelength of ripples on the surface. These methods all involve measuring the force needed to detach a geometric object from the surface and relating it to the surface tension. The units typically used for surface tension are mN/m or Newton metres/metre, and it can also be calculated by measuring the force on a unit length line on the surface of the liquid.
  • #1
derekmohammed
105
0
Hi,

Just a quick question:

How do you meausre surface tension of a liquid? WHat meathods are used and how do the units reflect the data.

Thanks

Derek Mohammed
 
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  • #2
You might have a look at the following site:
http://www.kruss.info/techniques/methods_overview_e.html#Wilhelmy_Plattenmethode [Broken]

Here is some further comments on the Du Nuoy ring method and Wuilhelmy plate method:
http://www.ksvinc.com/sigma703.htm [Broken]

Essentially it seems, each of these methods relies on relating the force needed to detach a simple geometric object from the liquid surface to the surface tension.
 
Last edited by a moderator:
  • #3
What do the units stand for? mN/m? Newton metres/ Metres??

Thanks
 
  • #4
mN=10^-3N and the denominator is in metres
 
  • #5
Presumably you could measure the velocity and wavelength of the "ripples" in a liquid to measure its surface tension, since it provides the restoring force for some waves on the surface. I'm sure there are other ways, though.
 
  • #6
Numerically Surface Tension (T):

[itex]T= \frac{F}{l}[/itex]

Infact, if you consider a unit length line on the surface of the water and measure the force on it from water on one side will give you Surface Tension. But that's not the 'experimental
method.
 

1. What is surface tension?

Surface tension is a physical property of liquids that describes the force that exists at the surface of a liquid, caused by the attraction between the liquid molecules. It is responsible for the formation of droplets and the ability of some insects to walk on water.

2. How is surface tension measured?

Surface tension is typically measured using a tensiometer, which is a device that measures the force required to pull a wire or plate from the surface of a liquid. Other common methods include using a capillary tube and measuring the height of the liquid column, or using a drop weight method to measure the force required to detach a drop from a surface.

3. What units are used to measure surface tension?

The most commonly used unit to measure surface tension is the SI unit, Newton per meter (N/m). Other units include dyne per centimeter (dyn/cm) and millinewton per meter (mN/m).

4. What factors can affect surface tension?

Surface tension can be affected by temperature, as it decreases with increasing temperature. It can also be affected by the type of liquid, with polar liquids having higher surface tension than non-polar liquids. Addition of solutes, such as salt, can also affect surface tension.

5. Why is measuring surface tension important?

Measuring surface tension is important in many industrial and scientific applications. It can help determine the purity and stability of liquids, as well as their ability to wet or adhere to surfaces. It is also useful in understanding the behavior of liquids in various processes, such as emulsion formation and bubble stability.

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