why does the surface tension of the water decrease on addition of detergent ?
why does the surface tension of the water decrease on addition of detergent ?
Surface tension of a liquid arises because of the high potential energy of the surface molecules of the liquid compared with the molecules residing at the bulk of the liquid. The molecules present at the surface has got higher potential energy because they are attracted by only other liquid molecules from one side and the upper layer is free from attraction. Now when detergent is added to water, the molecules of detergent spreads over the water surface and thus the water molecules are covered by detergent molecules. This, lowers the potential energy of the molecules and hence surface energy decreases. Decrease in the surface energy of the liquid leads into a decrease in the liquid’s surface tension.
Surface tension of a liquid arises because of the high potential energy of the surface molecules of the liquid compared with the molecules residing at the bulk of the liquid. The molecules present at the surface has got higher potential energy because they are attracted by only other liquid molecules from one side and the upper layer is free from attraction. Now when detergent is added to water, the molecules of detergent spreads over the water surface and thus the water molecules are covered by detergent molecules. This, lowers the potential energy of the molecules and hence surface energy decreases. Decrease in the surface energy of the liquid leads into a decrease in the liquid’s surface tension.
