Definitions
The concentration should move from diluted to concentrated when determining the surface tension of an aqueous n-butanol solution. This is the case because a solution's surface tension and concentration are inversely related.
Equilibrium Concentration of Butanol in a Solution
Equilibrium concentration should be used when calculating the surface tension of an aqueous n-butanol solution. This is due to the fact that as butanol dissolves in water, its concentration will alter.
Change in the Concentration of Butanol with Time
At larger concentrations, the surface tension of an aqueous n-butanol solution will increase because there are more hydrogen bonds forming between the water molecules and the alcohol molecules.
Conclusion
When calculating the surface tension, the concentration of the aqueous n-butanol solution should move from diluted to concentrated. This is due to the fact that when concentration rises, more water molecules become accessible to interact with the n-butanol molecule. Surface tension is reduced as a result of this interaction.
