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__Why is alcohol an effective antiseptic substance to use to clean skin?__


The molecular formula for ethanol is C2H5OH.

Bacteria have a cell membrane which is a selectively permeable lipid bilayer and it primarily contains lipids and proteins. In arrangement to the hydrophobic and hydrophilic, the polar lipids influence the diffusion of particles across the cell membrane. Lipids are impermeable to charged particles.

Alcohol is polar, which means that it has a negative charge, it can pass through the membrane. Once inside the bacteria in high concentration, the alcohol changes the normal solvent of the cell. Since alcohol is a polar solute and water is a polar solvent (Alcohol dissolves Water) they mix together through hydrogen bonds. Hydrogen bonds is an unusually strong dipole-dipole attractions in molecules where hydrogen is bonded to a highly electronegative atom. A dipole- dipole attraction is the force from when polar molecules line up so that the positive and negative end are close together. Do to the intermolecular forces being roughly equal, the molecules can form a new solution by breaking away from each other.

The new solution of water and alcohol causes the proteins to lose the structure that makes proteins perform its natural function in the membrane which leads the cell to swell and burst.

Pictures: http://www.webwombat.com.au/motoring/news_reports/images/ethanol2.JPG

http://www.nyu.edu/pages/mathmol/library/hydrocarbons/ethanol.gif

Cell information: http://en.wikipedia.org/wiki/Lipids

http://en.wikipedia.org/wiki/Bacterial_cell_structure