Composition and Structure of Petroleum
Petroleum is a complex mixture of hydrocarbons, including both liquid and solid paraffin, along with various other compounds. The main constituent is a mixture of hydrocarbons, but petroleum also contains nitrogen, oxygen, and even sulfur in varying but small concentrations. The composition of petroleum varies depending on the region in which it originated and the formation of which it is a part.
Petroleum is composed of a variety of organic molecules, including hydrocarbons, which are organic molecules composed only of hydrogen and carbon. These hydrocarbons come in a variety of forms, ranging from light, gaseous molecules called hydrogen and ethane to more complex and heavier molecules like benzene. Petroleum also contains other molecules such as nitrogen, oxygen and sulfur, although in varying and small amounts.
The structure of petroleum is somewhat complex and varies from formation to formation. Generally speaking, petroleum molecules are composed of long chains of carbon atoms that are joined by covalent bonds. These carbon atoms make up the backbone of the hydrocarbon molecule and may be linear or branched, depending on the molecule. The atoms linked to the carbon atoms are mostly hydrogen atoms, which can range from none to as many as twenty-five per molecule. Non-hydrocarbon molecules like oxygen and sulfur are usually either attached to the hydrocarbon backbone or present as a separate species in solution.
Petroleum can also contain trace amounts of metal ions such as sodium, magnesium, calcium, magnesium and calcium. These metal ions are often referred to as “ash,” and they are usually present in very small amounts, usually less than 0.0005%.
The physical property of petroleum is determined by the size, shape and distribution of the hydrocarbon molecules. Lighter, more volatile compounds tend to evaporate quickly at room temperature and pressure, while heavier hydrocarbon molecules remain in the liquid state. The viscosity of a petroleum product depends on the size and distribution of the hydrocarbons in the mixture. The higher the molecular weight, or the lower the vapor pressure, of the petroleum product, the higher the viscosity of the mixture, and the lower the flow rate.
In summary, petroleum is a complex mixture of hydrocarbons, nitrogen, oxygen and sulfur molecules in varying concentrations. The hydrocarbons are comprised of long chains of carbon atoms joined by covalent bonds, and petroleum can contain trace amounts of metal ions, known as “ash.” Petroleums physical properties depend on the size, shape and distribution of the hydrocarbon molecules, and the higher the molecular weight and lower the vapor pressure of a petroleum product, the higher the viscosity of the mixture and the lower the flow rate.
