Which Concentration of Ethanol is the Most Effective Bactericide

Question

Which concentration of ethanol is the most effective bactericide?
A)100 percent
B)70 percent
C)50 percent
D)40 percent
E)30 percent

Accepted Answer

A concentration of 70% ethanol is the most effective bactericide because it has a balance of water and alcohol to penetrate the cell membrane of bacteria and destroy it. Pure ethanol (100%) denatures proteins quickly, but it evaporates too quickly to penetrate the cell membrane. Lower concentrations (50% or less) may not denature proteins effectively due to not having enough alcohol.