The chemical formula for crude oil is CnH2n+2, where n is a positive integer. Crude oil is basically a combination of various hydrocarbon molecules, which comprise of hydrogen, H and carbon, C atoms.
Among the types of hydrocarbons present in crude oil, alkanes are predominant. Examples of such alkanes are ethane (C2H6), butane (C4H10) and propane (C3H8). Crude oil varies in composition, color and consistency based on the oil's hydrocarbon molecule combination. Light crude oil refers to high viscosity oil that has a light color and consistency. Its sulfur and metal content is low. Heavy crude oil's sulfur and metal content is high. Its viscosity is low, requiring heating for flow to occur.