Marangoni Effect

Marangoni effect is caused by a special property called surface tension. Surface tension is a tensile or contractile force on the surface. Every portion of the surface is pulling in on itself with a contractile force. So, if a liquid has a high surface tension, it means that its contractile force is high.

What happens when you put a drop of liquid with the low surface tension in a path of liquid with the high surface tension? Let use water and soap as an example; water has a high surface tension, while soap has a low surface tension. For each liquid, there is a contractile force on the surface. Since water has a higher surface tension than soap. So, contractile force on the surface is bigger for water than is for soap. In other words, water surface tension will pull stronger than soap surface tension. This results in a net force from region with low surface tension to region with high surface tension. This net force causes what is called the Marangoni Effect. The Marangoni Effect is that fluid rule wants to flow from area of lower surface tension to area of higher surface tension.

In the experiment, the boat is being propel when the soap on the end of the pencil lead is put in the water. This happens due to the Marangoni effect that pushes the boat forward. The soap coming out at the back of the boat because of the net force between liquid at different surface tension. The fluid coming out at the back of the boat is what propels the boat forward. This kind of repulsion works because of a Newton’s 3rd Law, which states that every action has an equal and opposite reaction. So, the action of the fluid coming out at the back of the boat produces a reaction in opposite direction, propelling the boat forward. However, the boat stops when the dissolving soap has reached the same concentration all over the water surface. This is because the intermolecular force between water molecules is broken. Once the force is broken, it will not reform spontaneously. So, the boat does not propel anymore.

Nowadays, Marangoni effect is applied in many field involved chemical engineering. One of the important application could be occurred in the device with continuous liquid phase, such as falling film absorber and packed distillation column. The absorption performance could be enhance by added saturated n-octanol vapor to the falling film absorber. Marangoni convection resulted when spreading and supporting liquids have different surface tension.

Another application that applies Marangoni effect is artificial rain by cloud seeding in nanotechnology. The nucleation of cloud drops depends on the supersaturation and on the aerosol particles. The chemical composition of the aerosol particles influences the water vapor pressure in the drop surfaces effect by modifying the surface tension of the drops. Dependent on the aerosol particles results in the surface tension of the drop can be higher or lower than that of pure water.

[ErenYaegerX]

creative and practical explanation, keep it up!

[SchweetOne]

Would someone falling into water from a very high height benefit from landing into soapy water since it will lower the surface tension? If so, could we raise the height we can cliff dive from by controlling the surface tension at the bottom?

[potterna]

Thanks. Very understandable explanation.

[si]

Great video! Can someone explain the engineering application?

[adosar]

How the gradient in surface tension translates to a net force in the boat? I can't understand it.

[sebastianosaccon]

this video is a nightmare but I gotta learn

[olgazinovieva]

Unfortunately, I don't understand your English and the subs are unavailable :( Thanks for your work anyway.

[zvish]

i like how the most interesting thing of this presentation which is the actual aplication was cut off down to 3 sekonds XDDDD and not explained at

[kevinf.]

that music is a) too loud b) not neccesary, im here for information not for party

[Seramics]

Belajau, jgn tak belajau. Apsal takde views, semua tau tgk viral je.