Disinfection & SafetyQuestion 27 of 100

Why is 70 percent isopropyl alcohol generally more effective as an antiseptic than 99 percent alcohol?

a.Because it is less expensive to produce
b.Because it evaporates faster and therefore contacts more organisms
c.Because higher concentrations are illegal in salons
d.Because the water content helps alcohol penetrate the cell wall, and the slower evaporation extends contact time

Explanation

Water in a 70 percent solution allows the alcohol to enter microbial cells rather than instantly coagulating the outer proteins, and the slower evaporation keeps the surface wet longer. Faster evaporation is a drawback, not a benefit. Cost is irrelevant to efficacy, and high-percentage alcohol is not itself illegal, just less effective as an antiseptic.

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