Exercises

1．Make sentences with the following words.

surfactant，surface tension，interfacial tension，surface free energy，lyophilic，lyophobic，amphipathic，aqueous，hydrophobic，hydrophilic，anionic，cationic，amphoteric，nonionic.

2．Give a more satisfactory definition to surfactant in Chinese according to the text.

3．Translate the following paragraph into Chinese.

The molecules at a surface have higher potential energies than those in the interior. This is because they interact more strongly with the molecules in the interior of the substance than they do with the widely spaced gas molecules above it. Work is therefore required to bring a molecule from the interior to the surface.

References

[1] ROSEN M J. Surfactants and Interfacial Phenomena [M]. 3rd ed. New York: John Wiley & Sons. Inc.，2004.

[2] ZETTLEMOYER A C. Colloid and Surface Chemistry [J]. Annual Review of Physical Chemistry，1958（9）: 439-468.