In a solution, molecules experience intermolecular forces with each other. However, the molecules in the surface of the solution experience less intermolecular force because part of it is exposed to a different phase. Therefore, there is a tendency for the “bulk” solution to pull the molecules from the surface towards them. This concept is applied in a rain droplet, where because of the pull by the bulk part of the solution, it shapes into a form of a sphere – a shape with the least surface …show more content…
Cohesion is the attraction of molecules within the same phase while adhesion refers to the attraction of molecules of different phases; say the n-butanol solution and the walls of the capillary tube. If the adhesion force is stronger than the cohesion force, the walls of the capillary tube will be wet, which in turn attracts molecules from the bulk of the solution upward until the pressure exerted from outside (environment) of the capillary tube is equal to the forces that lifts the solution upwards. This equilibrium point will be used to determine the height of the rise of the solution, which is a factor in determining the surface tension of the solution. Different concentrations of n-butanol solution were prepared in volumetric flasks. Then the radius of the capillary tube was identified by performing the capillary rise method using deionized water. With the given surface tension of water at 30 degrees Celsius, the radius was calculated: