# Time taken in changing surface tension

I had read some where that in glasses the surface tension is high, but in a lota the surface tension is low.

My question how much time does the surface tension take to change? I mean that there was water in a glass but I put it into a lota in how much time will the surface tension of water change? Immediately? This is a lota:

• Everyone, I am so sorry for using the wrong word. It is a lota not a burbot. I have also attached a image of lota – Daksh Shah Apr 8 '14 at 8:08
• @DakshShah No problem! Ask me about physicians and physicists on a bad day ;) Actually, the question whether the curvature of a lota bowl has an influence on the surface tension might be interesting, but unfortunately this is absolutely not my field of work. – Klaus-Dieter Warzecha Apr 8 '14 at 8:16
• @KlausWarzecha So you have no idea about this :( ? – Daksh Shah Apr 8 '14 at 8:23
• @DakshShah No, not really. But I have an unscientific gut feeling that if there is an effect at all (which I don't know for this macroscopic level) it will be instantaneous. You might want to google for surface tension curvature or wait for some anwers from people more versed in this field. – Klaus-Dieter Warzecha Apr 8 '14 at 8:32
• I don't get it... Isn't surface tension a property of the water, not the container that it resides in? A meniscus will form in both this container and a glass cup, won't it? If the lota isn't doing anything but holding the water inside, I wouldn't actually expect any change to water's surface tension. – rch Apr 10 '14 at 1:30

Just as a quick answer, because apparently some people are in doubt so let me try to clean up the confusion.

### The 'physics part'

Surface tension that people normally talk about is the liquid-air surface tension, in this case water-air, and I am pretty sure this is the surface tension you are referring to in your question. This water-air surface tension is a property of the water and air and has absolutely nothing to do with the physical shape or material of the container. For completeness, I have to mention that the contact with the walls that have different chemical properties will change the shape of the water-air interface a bit, which you might misinterpret as a change in water-air surface tension but this is caused by the water-container and container-air surface tensions which indeed DO depend on the container.

### The 'chemistry part'

What could * change the water-air surface tension is the exchange of some material out of the container into the water or the other way around. This would mean that you are not really looking at the water-air surface tension anymore, but rather at the (water$+$some solute)-air surface tension. Which might indeed be different, typically lower.

If this exchange is the mechanism then the time over which the surface tension will change is dependent on the kinetics of that process and without knowing what is being exchanged it is impossible to tell you what the time span will be, it could be seconds, it could be hours. Note that the explanation with stuff leaking out of or into the lota would mean that (assuming there will be equilibrium at some point) storing water in the lota and then drinking it from the glass would be the same as drinking it directly from the lota.

*I'm not saying it does I have no clue whether this happens with a lota

• I don't think there is only water/air surface tension. OP sees a difference between lota surface and glass surface. Maybe, one should also consider solid/liquid surface tension (for a lota and then for glass) and compare it with air/liquid... I would be interested in knowing whether water spreads out over a lota surface better than over a glass surface. – mannaia Apr 10 '14 at 7:28
• @mannaia - I discussed the other surface tensions as well - 'For completeness, I have to mention that the contact with the walls that have different chemical properties will change the shape of the water-air interface a bit, which you might misinterpret as a change in water-air surface tension but this is caused by the water-container and container-air surface tensions which indeed DO depend on the container. ' – Michiel Apr 10 '14 at 8:00
• @mannaia but judging by the question I really think the OP was thinking about the air-water surface tension. It would surprise me tremendously if water spreads better over the lota surface since (clean) household glass is already fully wetted by water – Michiel Apr 10 '14 at 8:02