How do you break the surface tension?
Adding surfactants the surface tension decrease.
How do we observe surface tension?
Small insects such can walk on water because their weight is not enough to penetrate the surface. A carefully placed small needle can be made to float on the surface of water even though it is several times as dense as water. If the surface is agitated to break up the surface tension, needle will quickly sink.
How can a sewing needle float on the surface of water?
The needle does not break the surface tension (meniscus). Get a small piece of toilet tissue and lay it on a glass of water. lay a needle on the tissue. The tissue will become sodden and sink, leaving the needle floating on the surface tension. Put the smallest drop of washing-up liquid on the water. The surface tension will be destroyed and the needle will sink. Try it.
Is surface tension effected by impurities?
yes The presence of impurities either on the surface or dissolved in it, affect surface tension of the liquid. Highly soluble substances increase the surface tension of water, whereas sparingly soluble substances reduce the surface tension of water. The surface tension of a liquid decreases with increase in temperature. The surface tension of a liquid becomes zero at its boiling point and vanishes at critical temperature.