Between 70% and 75%.

Alcohol, also known as ethanol, is usually divided into industrial alcohol, medical alcohol and civilian alcohol three clinically disinfected alcohol concentration is usually 75%, is a better disinfectant, can make bacterial proteins denatured, reduce bacterial activity, so as to achieve the purpose of eliminating bacteria.

If the concentration of alcohol is too high, it will make the bacterial protein concentration, the alcohol can not enter the protein inside, if the concentration of alcohol is too low, even if the alcohol into the protein inside, but also can not achieve the purpose of eliminating the bacteria, so the concentration of alcohol used in clinical use is usually between 70% and 75%.

Physical Properties

Ethanol is a saturated monohydric alcohol with one hydroxyl group, and can be viewed as the product of the substitution of a hydrogen atom by a hydroxyl group in an ethane molecule, or the substitution of a hydrogen atom by an ethyl group in a water molecule. The ethanol molecule is a polar molecule composed of C, H, and O atoms, where the C and O atoms are bonded in sp? hybridized orbitals.

Ethanol is a colorless, transparent, volatile, flammable, non-conductive liquid at room temperature and pressure, and its aqueous solution has a wine-like odor and a sweet taste. At 20 ℃ room temperature, ethanol liquid density is 0.789 g/cm? The melting point of ethanol is -114.1℃, boiling point is 78.3℃. Ethanol vapor can form explosive mixtures with air. 20 ℃, the refractive index of ethanol is 1.3611.

Ethanol is also a good solvent, can be dissolved with water in any ratio, can be miscible in chloroform, ethyl ether, acetic acid, methanol, acetone, glycerol and other most organic solvents.

Reference: Baidu Encyclopedia-Ethanol