Chemistry 22.5

Hydrocarbons From Earth’s Crust An artist imagines Saturn’s moon Titan as a refueling station in space. A traveler would refill a fuel tank with hydrocarbons from Titan’s atmosphere. On Earth, hydrocarbons are also used as fuels. You will learn about three fossil fuels—natural gas, petroleum, and coal.

Natural Gas What type of hydrocarbons are in natural gas? 22.5

Natural gas is an important source of alkanes of low molar mass. 22.5 Natural Gas Natural gas is an important source of alkanes of low molar mass. The most important component of natural gas, methane, burns with a clean, hot flame.

Wells are drilled to reach natural gas and petroleum. 22.5 Natural Gas Wells are drilled to reach natural gas and petroleum. Wells are drilled to reach natural gas and petroleum. Pressure from the trapped gas may force petroleum up a well pipe, but pumping is usually required.

Petroleum What is the first step in the refining of petroleum? 22.5

22.5 Petroleum The refining process starts with the distillation of petroleum (crude oil) into fractions according to boiling point. Cracking is a controlled process by which hydrocarbons are broken down or rearranged into smaller, more useful molecules.

Refineries separate crude oil into various components. 22.5 Petroleum Refineries separate crude oil into various components. Oil refineries To make gasoline, a refinery separates crude oil into various components. Refinery technicians combine some of the components, performance additives, and dyes to make different grades of fuel.

22.5 Petroleum In fractional distillation, the crude oil is heated so that it vaporizes and rises through the fractionating column. The column is hotter at the bottom and cooler at the top. In fractional distillation, the crude oil is heated so that it vaporizes and rises through the fractionating column. The column is hotter at the bottom and cooler at the top. Compounds with the highest boiling points condense near the bottom. Compounds with the lowest boiling points condense near the top.

22.5 Petroleum

22.5 Coal Coal How is coal classified?

Coal is classified by its hardness and carbon content. 22.5 Coal Coal is classified by its hardness and carbon content. Hardness of coal tends to increase with higher carbon content. Lignite ~50% carbon Bituminous 70–80% carbon Anthracite >80% carbon

22.5 Coal Coal Formation Coal formed when tree ferns and mosses died and were subjected to continued pressure and heat underground. Coal formed when tree ferns and mosses died. The layers of decaying organic material were compressed over millions of years between layers of soil and rock. The first stage in coal formation is peat. Continued pressure and heat transform peat into lignite, bituminous coal, and anthracite coal.

What is the chemical composition of coal? 22.5 Coal Composition of Coal What is the chemical composition of coal?

22.5 Coal Coal consists largely of condensed aromatic compounds of extremely high molar mass. These compounds have a high proportion of carbon compared with hydrogen.

Coal is mined from both surface mines and underground mines. 22.5 Coal Coal is mined from both surface mines and underground mines. Coal is mined from both surface mines, shown here, and underground mines.

22.5 Section Quiz. 22.5.

22.5 Section Quiz. 1. Which of the following is NOT a fossil fuel? petroleum natural gas coal alcohol

22.5 Section Quiz. 2. Coal usually generates more soot (unburned carbon particles) than does petroleum or natural gas because coal contains more condensed aromatic compounds. contains more aliphatic compounds. is a solid. contains sulfur compounds.

22.5 Section Quiz. 3. Crude oil is separated into gasoline, kerosene, and other products by means of combustion. fractional distillation. cracking. a catalyst.

Concept Map Concept Map 22 Solve the Concept Map with the help of an interactive guided tutorial.

END OF SHOW