What Are the Physical Properties of Octane?

Octane is a colorless and odorless liquid. It is volatile, very flammable and burns in air. This burning gives off carbon dioxide and water. Octane is less dense than water and basically insoluble in water.

Octane has a density of 0.703 grams per centimeters -3. As it can come in one of 18 isomers, octane has different melting points. These can range from minus 70.9 to minus 69.8 Fahrenheit. The boiling point of octane can vary between 257.1 and 258.9 degrees Fahrenheit. The vapor pressure is 1.47 kilopascals at about room temperature, or 68 degrees Fahrenheit. The viscosity of octane is 542 micropascal-seconds, also at room temperature. It has a flashpoint of 55.4 degrees Fahrenheit and an autoignition temperature of 428 degrees Fahrenheit.

Octane is a hydrocarbon, which makes it an organic molecule. It has eight carbon molecules and 18 hydrogen molecules. Because the octane molecule is made up solely of carbon and hydrogen and has no double or triple bonds or rings, it is considered an alkane.

Isooctane is a branched polymer of octane that is used to rate gasoline. Pure isooctane has an octane rating of 100. Since it burns very smoothly, it helps to decrease the amount of "knock" in the cylinders of a car engine.