It is generally black or dark brown in color (although it may be yellowish, reddish, or even greenish). It is typically found in reservoirs with natural gas, which, because it is lighter, forms a "gas cap" above the petroleum, and salty water, which, because it is heavier than other kinds of crude oil, sinks under it.
The word "petroleum" comes from the Greek petrolos, meaning "of the soil," referring to the belief that petroleum was once part of fertile soil that transformed itself through heat and pressure into a form usable by humans. Indeed, petroleum is a mixture of hydrocarbons (a group of carbon compounds containing hydrogen) derived from organic matter such as plants and animals that decompose over time due to heat and pressure from deep within the earth's crust. The term also refers to any substance composed primarily of hydrocarbon molecules including natural gas and asphalt, as well as their synthetic equivalents.
In chemistry, petroleum consists of a complex mixture of hydrocarbons, with different amounts of hydrogen and carbon atoms. The most abundant components are alkanes (chains of carbon atoms with hydrogen atoms attached to them), with smaller amounts of aromatic hydrocarbons (rings of carbon atoms with hydrogen atoms attached to them). Other substances present in small amounts include oxygen-containing compounds such as alcohols and aldehydes, and nitrogen-containing compounds such as amines and ammonia.
Petroleum (/[email protected]'[email protected]/), also known as crude oil or oil, is a naturally occurring, yellowish-black liquid found under the Earth's surface in geological formations. It is the remains of decayed plants and animals that have been compressed over time into porous rock where they can be extracted by drilling wells.
It is the largest source of fuel on earth, providing energy for almost every part of human activity. It is used to make gasoline, diesel fuel, heating oil, and even electricity.
Oil is composed of hydrocarbons: molecules consisting of hydrogen and carbon atoms. There are several types of hydrocarbon molecules including alkanes, alkenes, and aromatics. Oil contains these components in different proportions depending on how long it has been buried under ground. On average, oil is made up of about 75% alkanes and 25% alkenes by weight. However, the ratio of these two groups of compounds can vary significantly between oils. For example, the most saturated oil we know of is tetrapropylammonium chloride, which consists exclusively of alkanes with four carbons in their chains. This ratio results from empirical data collected by scientists who study geology through experiments using materials such as oil.
Alkanes are very stable molecules that do not easily break down into other substances.
When new, engine oil has a light brown hue, but it darkens as it goes through your car's engine, gathering dirt and combustion byproducts along the way. If you see a thick, slick liquid accumulating under your automobile that appears brown or black, you may have an engine oil leak. The smell can be quite unpleasant, too.
The best way to check for engine oil leaks is with an engine block scanner. These tools use radio frequency technology to detect openings in an engine block while it is running. They are very sensitive and can identify small holes as small as 0.1 mm (0.004 inches) in diameter. You can buy engine block scanners at auto parts stores for about $100. They are easy to use and will tell you right away if there are any problems with your engine block. If there are leaking oil galleries, these sensors will also alert you before more damage occurs.
If you don't have an engine block scanner, you can still check for leaks by using some basic skills and equipment. First, start your car and allow it to sit for a few minutes. This will allow any small leaks to drain out. Next, look for large stains on your driveway or parking lot caused by leaking oil. Finally, listen for pinging sounds coming from beneath your vehicle. This means there is air in your oil system and it needs to be released. Pinging sounds should go away once the air is removed.