How Does The Concentration Of Substances To Water Change Its Surface Tension?

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Main goal of the experiment
The main goal of experiment is to determine, how adding different substances to water changes its surface tension, and how the concentration of those solutions influences surface tension. We would also like to examine, which of the chosen experimental method is more precise, reliable and efficient.
Theoretical background of the experiment
Surface tension is a physical phenomenon existing on contacting surface of liquid with gas, solid or other liquid, causing that the surface acts as elastic membrane. It may be also described as property of surface of liquid enabling it to resist an external force. Its mechanism is due to cohesive forces between molecules of liquid. The molecules are pulled in every direction by neighbouring ones. In the bulk of liquid, resultant pulling force is zero. However, as molecules approach the surface, pulling forces from one side become significantly smaller. This causes drawing of molecules backwards to the bulk. As overall effect, liquids tend to mass maximum of their molecules inside, which results in shaping surfaces in such a way to minimize their area (USGS Water Science School website). …show more content…

solids soluble in that liquid or other liquids, which are miscible with that under investigation. Substances that will be investigated during this experiment, i.e. dishwashing liquids and washing powders, belong to group called surface active agents, or, in short, surfactants. Their ability of lowering surface tension of solution is useful in processes of washing, cleaning etc.
Quantitatively, surface tension, denoted as γ, is described as work W required to change surface area of a liquid by a unit area

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