Chemistry & Electricity第 82 / 100 题
Which statement about emulsions used in skin care is accurate?
a.An emulsion is a single pure substance with no separate phases
b.An emulsion is a mixture of oil and water held together by a surfactant, and it may be oil-in-water or water-in-oil
c.All emulsions are water-in-oil and feel heavy on the skin
d.Emulsions do not require an emulsifying agent
解析
An emulsion suspends one immiscible liquid inside another, and a surfactant or emulsifier keeps the droplets dispersed so the product does not separate. Oil-in-water emulsions feel lighter and are common in lotions, while water-in-oil emulsions are richer and more occlusive. Without an emulsifier the phases separate, and an emulsion is by definition a mixture, not a pure substance.
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