Ethanol, C2H5OH

Ethanol is a colorless liquid with a typical smell. The chemical structure is polar in one end due to the OH-group and therefore the molecules can dissolve in various solvents.

Ethanol (EtOH, C2H5OH) structure in two variants.


Even a low ethanol concentration causes irritated eyes or skin. Occupational exposure limits for a 8-hour reference period is 500 ppm (1000 mg/m³) and level limit is 1000 ppm (1900 mg/m3). The most characteristic peaks in the IR spectrum of ethanol come from various C-H bonds and from the C-O bond.


Ethanol and drunk driving

The ethanol content is expressed in various ways around the world. For example, the unit of blood alcohol contration, BAC, is % in USA, which means g ethanol per 100 ml blood. In Sweden it is ‰ by mass, mg ethanol per g blood. Normal blood weighs about 1.06 g / ml. Also, every country has their own regulation concerning ethanol and driving. The following limits can be found:


1 June 2010, car or boat driving in Sweden

Blood alcohol concentration <0.2 ‰, by mass, mg EtOH / g blood Breath alcohol concentration <0.10 mg EtOH / dm3 air


2011, car driving for entire USA

Blood alcohol concentration <0.08 %, g EtOH /100 ml blood. If the driver is <21 years old it is zero tolerance!

Breath alcohol concentration <0.37 mg EtOH/dm3 air


IR spectrum of ethanol

The broadest peak in the IR spectrum of ethanol comes from O-H stretches, similar to O-H bonds in water. This absorption at 3400 cm-1 corresponds to a wavelength of about 2.9 µm. Other strong streching modes are C-H at 3000 cm-1 and C-O at 1050 cm-1, corresponding to 3.3 µm and 9.5 µm, respectively.

This IR spectrum is copied from tutorial pages by Organic Chemistry at Colorado University, USA. Read more